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при обращении к свойству объекта?","best_answer_id":490,"related_stacks_count":5},"answers":[{"user":{"id":75907,"email":"dzencot@gmail.com","first_name":"Ivan","last_name":"Gagarinov","telegram":"igagarinov","full_name":"Ivan Gagarinov","removed":false},"question":{"creator":{"id":75907,"email":"dzencot@gmail.com","first_name":"Ivan","last_name":"Gagarinov","telegram":"igagarinov","full_name":"Ivan Gagarinov","removed":false},"category":{"id":2,"title":"JavaScript","slug":"javascript","questions_count":852,"locale":"ru"},"tags":[{"id":633,"slug":"javascript","name":"JavaScript"},{"id":287,"slug":"ob-ekty","name":"Объекты"},{"id":793,"slug":"objects","name":"objects"},{"id":571,"slug":"js","name":"JS"},{"id":710,"slug":"property","name":"property"}],"id":1964,"answers_count":2,"slug":"chto-oznachaet-znak-voprosa-v-stroke-comment-author","state":"published","title":"Что означает знак вопроса в строке comment?.author","created_at":"2022-07-12T16:39:28.603Z","details":"Для чего ставится знак вопроса перед точкой при обращении к свойству объекта?","best_answer_id":490,"related_stacks_count":5},"id":490,"state":"active","body":"Этот оператор называется \"оператор опциональной последовательности\". Он позволяет обращаться в нутренним свойствам объекта, без риска что родительское свойство отсутствует в объекте. Чтобы лучше это понять, разберем пример.\r\n\r\nПредположим у нас есть сущности пользователей с их адресами в виде объектов по типу:\r\n\r\n```javascript\r\nconst user = {\r\n name: 'Ivan',\r\n age: 29,\r\n address: {\r\n country: 'Russia',\r\n city: 'Perm',\r\n street: 'Leonova',\r\n },\r\n};\r\n```\r\n\r\nПредположим мы хотим сформировать строку содержащую страну и город пользователя `Russia, Perm`. Для этого мы просто обращаемся к внутренним ключам объекта в ключе `address`:\r\n\r\n```javascript\r\nconst result = `${user.address.country}, ${user.address.city}`;\r\nconsole.log(result); // => Russia, Perm\r\n```\r\n\r\nНо что если у нас будет пользователь с отсутствующим адресом? Такой код выдаст ошибку, потому что мы попытались обратиться к свойствам `country` и `city` у значения `undefined`:\r\n\r\n```javscript\r\nconst homelessUser = {\r\n name: 'Ivan',\r\n age: 29,\r\n};\r\nconst result = `${homelessUser.address.country}, ${homelessUser.address.city}`; // TypeError: Cannot read properties of undefined (reading 'country')\r\nconsole.log(result);\r\n```\r\n\r\nУ объекта `user` нет свойства `address`, поэтому мы не можем к обратиться к нему. Чтобы избежать такой ошибки, используется оператор опциональной последовательности: добавляется знак вопроса после свойства, которого может не быть в объекте. Такой код уже не выдаст ошибку:\r\n\r\n```javscript\r\nconst homelessUser = {\r\n name: 'Ivan',\r\n age: 29,\r\n};\r\nconst result = `${homelessUser.address?.country}, ${homelessUser.address?.city}`;\r\nconsole.log(result); // => undefined, undefined\r\n```\r\n\r\nНе смотря на то, что это удобный инструмент, бездумно его использовать не стоит. Обычно его использование говорит о том, что в приложении есть проблемы. Например, в примере выше, должна стоять проверка на существование адреса пользователя. Если адреса нет, то нет смысла составлять строку. Если добавить такую проверку, то необходимость в использовании этого оператора отпадает.","votes_up_count":2,"votes_down_count":0,"created_at":"2022-07-13T04:47:55.728Z","user_id":75907,"category_slug":"javascript"},{"user":{"id":319860,"email":"alekskob33@yandex.ru","first_name":"Aleksey","last_name":"","telegram":"alekskob33","full_name":"Aleksey","removed":false},"question":{"creator":{"id":75907,"email":"dzencot@gmail.com","first_name":"Ivan","last_name":"Gagarinov","telegram":"igagarinov","full_name":"Ivan Gagarinov","removed":false},"category":{"id":2,"title":"JavaScript","slug":"javascript","questions_count":852,"locale":"ru"},"tags":[{"id":633,"slug":"javascript","name":"JavaScript"},{"id":287,"slug":"ob-ekty","name":"Объекты"},{"id":793,"slug":"objects","name":"objects"},{"id":571,"slug":"js","name":"JS"},{"id":710,"slug":"property","name":"property"}],"id":1964,"answers_count":2,"slug":"chto-oznachaet-znak-voprosa-v-stroke-comment-author","state":"published","title":"Что означает знак вопроса в строке comment?.author","created_at":"2022-07-12T16:39:28.603Z","details":"Для чего ставится знак вопроса перед точкой при обращении к свойству объекта?","best_answer_id":490,"related_stacks_count":5},"id":2275,"state":"active","body":"Подробнее о том, когда лучше отказаться от использования `?.` оператора:\r\n\r\n1. Когда необходимо явно обработать отсутствие значения. Например, если мы ожидаем, что свойство объекта будет иметь определенное значение, и если его нет, то нужно выполнить какие-то дополнительные действия.\r\n\r\n2. Когда нужно обеспечить совместимость с более старыми версиями JavaScript. Оператор опциональной последовательности был добавлен в ECMAScript 2020, поэтому его использование может привести к проблемам совместимости с более старыми браузерами или средами выполнения JavaScript.\r\n\r\n3. Когда нужно улучшить читаемость кода. Иногда использование оператора опциональной последовательности может усложнить чтение кода, особенно если он содержит множество вложенных свойств и методов.\r\n","votes_up_count":0,"votes_down_count":0,"created_at":"2023-04-05T17:58:49.107Z","user_id":319860,"category_slug":"javascript"}],"relatedQuestions":[{"creator":{"id":363630,"email":"a.agaphonov@ya.ru","first_name":"Человек-Молекула","last_name":"","telegram":null,"full_name":"Человек-Молекула","removed":false},"category":{"id":2,"title":"JavaScript","slug":"javascript","questions_count":852,"locale":"ru"},"tags":[],"id":1359,"answers_count":1,"slug":"kak-sdelat-drag-and-drop-javascript","state":"published","title":"Как сделать drag and drop 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js\r","created_at":"2021-12-20T13:37:31.322Z","details":null,"best_answer_id":2215,"related_stacks_count":5},{"creator":{"id":363630,"email":"a.agaphonov@ya.ru","first_name":"Человек-Молекула","last_name":"","telegram":null,"full_name":"Человек-Молекула","removed":false},"category":{"id":2,"title":"JavaScript","slug":"javascript","questions_count":852,"locale":"ru"},"tags":[],"id":1365,"answers_count":1,"slug":"kak-sdelat-plavnyy-skroll-js","state":"published","title":"Как сделать плавный скролл js\r","created_at":"2021-12-20T13:37:31.288Z","details":null,"best_answer_id":1917,"related_stacks_count":5}],"relatedLandings":[{"stack":{"id":52,"slug":"typescript","title":"Typescript","audience":"for_programmers","start_type":"anytime","pricing_model":"subscription","priority":"medium","kind":"track","state":"published","stack_state":"finished","order":200,"duration_in_months":2},"id":92,"slug":"typescript","title":"Typescript","subtitle":"Навык снижать ошибки, упрощать отладку, повышать 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Он позволяет обращаться в нутренним свойствам объекта, без риска что родительское свойство отсутствует в объекте. Чтобы лучше это понять, разберем пример.\r\n\r\nПредположим у нас есть сущности пользователей с их адресами в виде объектов по типу:\r\n\r\n```javascript\r\nconst user = {\r\n name: 'Ivan',\r\n age: 29,\r\n address: {\r\n country: 'Russia',\r\n city: 'Perm',\r\n street: 'Leonova',\r\n },\r\n};\r\n```\r\n\r\nПредположим мы хотим сформировать строку содержащую страну и город пользователя `Russia, Perm`. Для этого мы просто обращаемся к внутренним ключам объекта в ключе `address`:\r\n\r\n```javascript\r\nconst result = `${user.address.country}, ${user.address.city}`;\r\nconsole.log(result); // => Russia, Perm\r\n```\r\n\r\nНо что если у нас будет пользователь с отсутствующим адресом? Такой код выдаст ошибку, потому что мы попытались обратиться к свойствам `country` и `city` у значения `undefined`:\r\n\r\n```javscript\r\nconst homelessUser = {\r\n name: 'Ivan',\r\n age: 29,\r\n};\r\nconst result = `${homelessUser.address.country}, ${homelessUser.address.city}`; // TypeError: Cannot read properties of undefined (reading 'country')\r\nconsole.log(result);\r\n```\r\n\r\nУ объекта `user` нет свойства `address`, поэтому мы не можем к обратиться к нему. Чтобы избежать такой ошибки, используется оператор опциональной последовательности: добавляется знак вопроса после свойства, которого может не быть в объекте. Такой код уже не выдаст ошибку:\r\n\r\n```javscript\r\nconst homelessUser = {\r\n name: 'Ivan',\r\n age: 29,\r\n};\r\nconst result = `${homelessUser.address?.country}, ${homelessUser.address?.city}`;\r\nconsole.log(result); // => undefined, undefined\r\n```\r\n\r\nНе смотря на то, что это удобный инструмент, бездумно его использовать не стоит. Обычно его использование говорит о том, что в приложении есть проблемы. Например, в примере выше, должна стоять проверка на существование адреса пользователя. Если адреса нет, то нет смысла составлять строку. Если добавить такую проверку, то необходимость в использовании этого оператора отпадает.","datePublished":"2022-07-13T04:47:55.728Z","upvoteCount":2,"author":{"@type":"Person","name":"Ivan Gagarinov"},"url":"https://ru.hexlet.io/qna/javascript/questions/chto-oznachaet-znak-voprosa-v-stroke-comment-author#answer-490"},"suggestedAnswer":[{"@type":"Answer","text":"Подробнее о том, когда лучше отказаться от использования `?.` оператора:\r\n\r\n1. Когда необходимо явно обработать отсутствие значения. Например, если мы ожидаем, что свойство объекта будет иметь определенное значение, и если его нет, то нужно выполнить какие-то дополнительные действия.\r\n\r\n2. Когда нужно обеспечить совместимость с более старыми версиями JavaScript. Оператор опциональной последовательности был добавлен в ECMAScript 2020, поэтому его использование может привести к проблемам совместимости с более старыми браузерами или средами выполнения JavaScript.\r\n\r\n3. Когда нужно улучшить читаемость кода. Иногда использование оператора опциональной последовательности может усложнить чтение кода, особенно если он содержит множество вложенных свойств и методов.\r\n","datePublished":"2023-04-05T17:58:49.107Z","upvoteCount":0,"author":{"@type":"Person","name":"Aleksey"},"url":"https://ru.hexlet.io/qna/javascript/questions/chto-oznachaet-znak-voprosa-v-stroke-comment-author#answer-2275"}]}}</script><div style="--container-size:var(--container-size-lg);margin-top:var(--mantine-spacing-xl);height:100%" class="m_7485cace mantine-Container-root" data-size="lg" data-strategy="block"><script type="application/ld+json">{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"position":1,"@type":"ListItem","item":{"@id":"/qna","name":"Вопросы и 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class="mantine-focus-auto m_849cf0da m_b6d8b162 mantine-Text-root mantine-Anchor-root" data-underline="hover" href="/qna/javascript/tags/ob-ekty"><div style="--badge-height:var(--badge-height-sm);--badge-padding-x:var(--badge-padding-x-sm);--badge-fz:var(--badge-fz-sm);--badge-bg:var(--mantine-color-default);--badge-color:var(--mantine-color-default-color);--badge-bd:calc(0.0625rem * var(--mantine-scale)) solid var(--mantine-color-default-border);cursor:pointer" class="m_347db0ec mantine-Badge-root" data-variant="default" data-size="sm"><span class="m_5add502a mantine-Badge-label">Объекты</span></div></a><a class="mantine-focus-auto m_849cf0da m_b6d8b162 mantine-Text-root mantine-Anchor-root" data-underline="hover" href="/qna/javascript/tags/objects"><div style="--badge-height:var(--badge-height-sm);--badge-padding-x:var(--badge-padding-x-sm);--badge-fz:var(--badge-fz-sm);--badge-bg:var(--mantine-color-default);--badge-color:var(--mantine-color-default-color);--badge-bd:calc(0.0625rem * var(--mantine-scale)) solid var(--mantine-color-default-border);cursor:pointer" class="m_347db0ec mantine-Badge-root" data-variant="default" data-size="sm"><span class="m_5add502a mantine-Badge-label">objects</span></div></a><a class="mantine-focus-auto m_849cf0da m_b6d8b162 mantine-Text-root mantine-Anchor-root" data-underline="hover" href="/qna/javascript/tags/js"><div style="--badge-height:var(--badge-height-sm);--badge-padding-x:var(--badge-padding-x-sm);--badge-fz:var(--badge-fz-sm);--badge-bg:var(--mantine-color-default);--badge-color:var(--mantine-color-default-color);--badge-bd:calc(0.0625rem * var(--mantine-scale)) solid var(--mantine-color-default-border);cursor:pointer" class="m_347db0ec mantine-Badge-root" data-variant="default" data-size="sm"><span class="m_5add502a mantine-Badge-label">JS</span></div></a><a class="mantine-focus-auto m_849cf0da m_b6d8b162 mantine-Text-root mantine-Anchor-root" data-underline="hover" href="/qna/javascript/tags/property"><div style="--badge-height:var(--badge-height-sm);--badge-padding-x:var(--badge-padding-x-sm);--badge-fz:var(--badge-fz-sm);--badge-bg:var(--mantine-color-default);--badge-color:var(--mantine-color-default-color);--badge-bd:calc(0.0625rem * var(--mantine-scale)) solid var(--mantine-color-default-border);cursor:pointer" class="m_347db0ec mantine-Badge-root" data-variant="default" data-size="sm"><span class="m_5add502a mantine-Badge-label">property</span></div></a></div><div style="margin-bottom:var(--mantine-spacing-xs)" class="m_d08caa0 mantine-Typography-root"><p>Для чего ставится знак вопроса перед точкой при обращении к свойству объекта?</p></div><div style="--group-gap:var(--mantine-spacing-md);--group-align:center;--group-justify:flex-start;--group-wrap:wrap;margin-bottom:var(--mantine-spacing-xl);font-size:var(--mantine-font-size-sm)" class="m_4081bf90 mantine-Group-root"><div style="--group-gap:calc(0.25rem * var(--mantine-scale));--group-align:center;--group-justify:flex-start;--group-wrap:wrap;margin-inline-start:auto" class="m_4081bf90 mantine-Group-root"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="tabler-icon tabler-icon-calendar "><path d="M4 7a2 2 0 0 1 2 -2h12a2 2 0 0 1 2 2v12a2 2 0 0 1 -2 2h-12a2 2 0 0 1 -2 -2v-12"></path><path d="M16 3v4"></path><path d="M8 3v4"></path><path d="M4 11h16"></path><path d="M11 15h1"></path><path d="M12 15v3"></path></svg><p class="mantine-focus-auto m_b6d8b162 mantine-Text-root" data-inherit="true">4 года назад</p></div><div style="--group-gap:calc(0.25rem * var(--mantine-scale));--group-align:center;--group-justify:flex-start;--group-wrap:wrap" class="m_4081bf90 mantine-Group-root"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="tabler-icon tabler-icon-user "><path d="M8 7a4 4 0 1 0 8 0a4 4 0 0 0 -8 0"></path><path d="M6 21v-2a4 4 0 0 1 4 -4h4a4 4 0 0 1 4 4v2"></path></svg><p class="mantine-focus-auto m_b6d8b162 mantine-Text-root" data-inherit="true">Ivan Gagarinov</p></div></div><div role="link" tabindex="0" style="cursor:pointer"><button style="display:block;width:100%" class="mantine-focus-auto m_87cf2631 mantine-UnstyledButton-root" type="button" aria-label="Присоединяйтесь к нашему Telegram-сообществу"><div style="background-color:light-dark(var(--mantine-color-gray-1), var(--mantine-color-dark-6));margin-block:var(--mantine-spacing-xs)" class="m_e615b15f mantine-Card-root m_1b7284a3 mantine-Paper-root"><div style="--group-gap:var(--mantine-spacing-md);--group-align:center;--group-justify:flex-start;--group-wrap:wrap" class="m_4081bf90 mantine-Group-root"><div style="--ti-bg:transparent;--ti-color:var(--mantine-color-indigo-light-color);--ti-bd:calc(0.0625rem * var(--mantine-scale)) solid transparent;margin-inline-end:auto;color:inherit" class="m_7341320d mantine-ThemeIcon-root" data-variant="transparent"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.2" stroke-linecap="round" stroke-linejoin="round" class="tabler-icon tabler-icon-brand-telegram "><path d="M15 10l-4 4l6 6l4 -16l-18 7l4 2l2 6l3 -4"></path></svg></div>Присоединяйтесь к нашему Telegram-сообществу</div></div></button></div><h2 style="--title-fw:var(--mantine-h2-font-weight);--title-lh:var(--mantine-h2-line-height);--title-fz:var(--mantine-h2-font-size);margin-block:var(--mantine-spacing-xl)" class="m_8a5d1357 mantine-Title-root" data-order="2">Ответы</h2><div style="margin-bottom:var(--mantine-spacing-xl);padding:var(--mantine-spacing-lg)" class="m_e615b15f mantine-Card-root m_1b7284a3 mantine-Paper-root" data-with-border="true" id="answer-490"><div style="--group-gap:calc(1.125rem * var(--mantine-scale));--group-align:stretch;--group-justify:flex-start;--group-wrap:nowrap" class="m_4081bf90 mantine-Group-root"><div style="--stack-gap:var(--mantine-spacing-md);--stack-align:stretch;--stack-justify:flex-start;font-size:var(--mantine-font-size-h1);font-weight:lighter;text-align:center" class="m_6d731127 mantine-Stack-root">2<a style="color:inherit" class="mantine-focus-auto m_849cf0da m_b6d8b162 mantine-Text-root mantine-Anchor-root" data-underline="hover" href="/qna/javascript/questions/chto-oznachaet-znak-voprosa-v-stroke-comment-author/answers/490/vote"><div style="--ti-bg:transparent;--ti-color:var(--mantine-color-indigo-light-color);--ti-bd:calc(0.0625rem * var(--mantine-scale)) solid transparent;color:inherit" class="m_7341320d mantine-ThemeIcon-root" data-variant="transparent"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="tabler-icon tabler-icon-thumb-up "><path d="M7 11v8a1 1 0 0 1 -1 1h-2a1 1 0 0 1 -1 -1v-7a1 1 0 0 1 1 -1h3a4 4 0 0 0 4 -4v-1a2 2 0 0 1 4 0v5h3a2 2 0 0 1 2 2l-1 5a2 3 0 0 1 -2 2h-7a3 3 0 0 1 -3 -3"></path></svg></div></a><div style="--ti-bg:transparent;--ti-color:var(--mantine-color-indigo-light-color);--ti-bd:calc(0.0625rem * var(--mantine-scale)) solid transparent;color:inherit" class="m_7341320d mantine-ThemeIcon-root" data-variant="transparent"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="tabler-icon tabler-icon-check "><path d="M5 12l5 5l10 -10"></path></svg></div></div><div style="--stack-gap:var(--mantine-spacing-md);--stack-align:stretch;--stack-justify:flex-start;width:100%;min-width:0rem" class="m_6d731127 mantine-Stack-root"><div style="margin-bottom:auto" class="m_d08caa0 mantine-Typography-root"><p>Этот оператор называется "оператор опциональной последовательности". Он позволяет обращаться в нутренним свойствам объекта, без риска что родительское свойство отсутствует в объекте. Чтобы лучше это понять, разберем пример.</p>
<p>Предположим у нас есть сущности пользователей с их адресами в виде объектов по типу:</p>
<div style="margin-bottom:var(--mantine-spacing-lg)" class="m_e597c321 mantine-CodeHighlight-codeHighlight" dir="ltr"><div class="m_be7e9c9c mantine-CodeHighlight-controls"><button style="--ai-bg:transparent;--ai-hover:transparent;--ai-color:inherit;--ai-bd:none" class="mantine-focus-auto mantine-active m_d498bab7 mantine-CodeHighlight-control m_8d3f4000 mantine-ActionIcon-root m_87cf2631 mantine-UnstyledButton-root" data-variant="none" type="button" aria-label="Copy code"><span class="m_8d3afb97 mantine-ActionIcon-icon"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" fill="none" stroke-linecap="round" stroke-linejoin="round"><path stroke="none" d="M0 0h24v24H0z" fill="none"></path><path d="M8 8m0 2a2 2 0 0 1 2 -2h8a2 2 0 0 1 2 2v8a2 2 0 0 1 -2 2h-8a2 2 0 0 1 -2 -2z"></path><path d="M16 8v-2a2 2 0 0 0 -2 -2h-8a2 2 0 0 0 -2 2v8a2 2 0 0 0 2 2h2"></path></svg></span></button></div><div style="--scrollarea-scrollbar-size:calc(0.25rem * var(--mantine-scale));--sa-corner-width:0px;--sa-corner-height:0px" class="m_f744fd40 mantine-CodeHighlight-scrollarea m_d57069b5 mantine-ScrollArea-root" dir="ltr"><div style="overflow-x:hidden;overflow-y:hidden;overscroll-behavior-inline:none" class="m_c0783ff9 mantine-ScrollArea-viewport" data-scrollbars="xy"><div class="m_b1336c6 mantine-ScrollArea-content"><pre class="m_2c47c4fd mantine-CodeHighlight-pre" style="padding:0"><code class="m_5caae6d3 mantine-CodeHighlight-code">const user = {
name: 'Ivan',
age: 29,
address: {
country: 'Russia',
city: 'Perm',
street: 'Leonova',
},
};</code></pre></div></div></div><button class="mantine-focus-auto m_c9378bc2 mantine-CodeHighlight-showCodeButton m_87cf2631 mantine-UnstyledButton-root" data-hidden="true" type="button">Expand code</button></div>
<p>Предположим мы хотим сформировать строку содержащую страну и город пользователя <code style="margin-bottom:var(--mantine-spacing-lg)" class="m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight m_e597c321 mantine-CodeHighlight-codeHighlight m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight">Russia, Perm</code>. Для этого мы просто обращаемся к внутренним ключам объекта в ключе <code style="margin-bottom:var(--mantine-spacing-lg)" class="m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight m_e597c321 mantine-CodeHighlight-codeHighlight m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight">address</code>:</p>
<div style="margin-bottom:var(--mantine-spacing-lg)" class="m_e597c321 mantine-CodeHighlight-codeHighlight" dir="ltr"><div class="m_be7e9c9c mantine-CodeHighlight-controls"><button style="--ai-bg:transparent;--ai-hover:transparent;--ai-color:inherit;--ai-bd:none" class="mantine-focus-auto mantine-active m_d498bab7 mantine-CodeHighlight-control m_8d3f4000 mantine-ActionIcon-root m_87cf2631 mantine-UnstyledButton-root" data-variant="none" type="button" aria-label="Copy code"><span class="m_8d3afb97 mantine-ActionIcon-icon"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" fill="none" stroke-linecap="round" stroke-linejoin="round"><path stroke="none" d="M0 0h24v24H0z" fill="none"></path><path d="M8 8m0 2a2 2 0 0 1 2 -2h8a2 2 0 0 1 2 2v8a2 2 0 0 1 -2 2h-8a2 2 0 0 1 -2 -2z"></path><path d="M16 8v-2a2 2 0 0 0 -2 -2h-8a2 2 0 0 0 -2 2v8a2 2 0 0 0 2 2h2"></path></svg></span></button></div><div style="--scrollarea-scrollbar-size:calc(0.25rem * var(--mantine-scale));--sa-corner-width:0px;--sa-corner-height:0px" class="m_f744fd40 mantine-CodeHighlight-scrollarea m_d57069b5 mantine-ScrollArea-root" dir="ltr"><div style="overflow-x:hidden;overflow-y:hidden;overscroll-behavior-inline:none" class="m_c0783ff9 mantine-ScrollArea-viewport" data-scrollbars="xy"><div class="m_b1336c6 mantine-ScrollArea-content"><pre class="m_2c47c4fd mantine-CodeHighlight-pre" style="padding:0"><code class="m_5caae6d3 mantine-CodeHighlight-code">const result = `${user.address.country}, ${user.address.city}`;
console.log(result); // => Russia, Perm</code></pre></div></div></div><button class="mantine-focus-auto m_c9378bc2 mantine-CodeHighlight-showCodeButton m_87cf2631 mantine-UnstyledButton-root" data-hidden="true" type="button">Expand code</button></div>
<p>Но что если у нас будет пользователь с отсутствующим адресом? Такой код выдаст ошибку, потому что мы попытались обратиться к свойствам <code style="margin-bottom:var(--mantine-spacing-lg)" class="m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight m_e597c321 mantine-CodeHighlight-codeHighlight m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight">country</code> и <code style="margin-bottom:var(--mantine-spacing-lg)" class="m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight m_e597c321 mantine-CodeHighlight-codeHighlight m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight">city</code> у значения <code style="margin-bottom:var(--mantine-spacing-lg)" class="m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight m_e597c321 mantine-CodeHighlight-codeHighlight m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight">undefined</code>:</p>
<div style="margin-bottom:var(--mantine-spacing-lg)" class="m_e597c321 mantine-CodeHighlight-codeHighlight" dir="ltr"><div class="m_be7e9c9c mantine-CodeHighlight-controls"><button style="--ai-bg:transparent;--ai-hover:transparent;--ai-color:inherit;--ai-bd:none" class="mantine-focus-auto mantine-active m_d498bab7 mantine-CodeHighlight-control m_8d3f4000 mantine-ActionIcon-root m_87cf2631 mantine-UnstyledButton-root" data-variant="none" type="button" aria-label="Copy code"><span class="m_8d3afb97 mantine-ActionIcon-icon"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" fill="none" stroke-linecap="round" stroke-linejoin="round"><path stroke="none" d="M0 0h24v24H0z" fill="none"></path><path d="M8 8m0 2a2 2 0 0 1 2 -2h8a2 2 0 0 1 2 2v8a2 2 0 0 1 -2 2h-8a2 2 0 0 1 -2 -2z"></path><path d="M16 8v-2a2 2 0 0 0 -2 -2h-8a2 2 0 0 0 -2 2v8a2 2 0 0 0 2 2h2"></path></svg></span></button></div><div style="--scrollarea-scrollbar-size:calc(0.25rem * var(--mantine-scale));--sa-corner-width:0px;--sa-corner-height:0px" class="m_f744fd40 mantine-CodeHighlight-scrollarea m_d57069b5 mantine-ScrollArea-root" dir="ltr"><div style="overflow-x:hidden;overflow-y:hidden;overscroll-behavior-inline:none" class="m_c0783ff9 mantine-ScrollArea-viewport" data-scrollbars="xy"><div class="m_b1336c6 mantine-ScrollArea-content"><pre class="m_2c47c4fd mantine-CodeHighlight-pre" style="padding:0"><code class="m_5caae6d3 mantine-CodeHighlight-code">const homelessUser = {
name: 'Ivan',
age: 29,
};
const result = `${homelessUser.address.country}, ${homelessUser.address.city}`; // TypeError: Cannot read properties of undefined (reading 'country')
console.log(result);</code></pre></div></div></div><button class="mantine-focus-auto m_c9378bc2 mantine-CodeHighlight-showCodeButton m_87cf2631 mantine-UnstyledButton-root" data-hidden="true" type="button">Expand code</button></div>
<p>У объекта <code style="margin-bottom:var(--mantine-spacing-lg)" class="m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight m_e597c321 mantine-CodeHighlight-codeHighlight m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight">user</code> нет свойства <code style="margin-bottom:var(--mantine-spacing-lg)" class="m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight m_e597c321 mantine-CodeHighlight-codeHighlight m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight">address</code>, поэтому мы не можем к обратиться к нему. Чтобы избежать такой ошибки, используется оператор опциональной последовательности: добавляется знак вопроса после свойства, которого может не быть в объекте. Такой код уже не выдаст ошибку:</p>
<div style="margin-bottom:var(--mantine-spacing-lg)" class="m_e597c321 mantine-CodeHighlight-codeHighlight" dir="ltr"><div class="m_be7e9c9c mantine-CodeHighlight-controls"><button style="--ai-bg:transparent;--ai-hover:transparent;--ai-color:inherit;--ai-bd:none" class="mantine-focus-auto mantine-active m_d498bab7 mantine-CodeHighlight-control m_8d3f4000 mantine-ActionIcon-root m_87cf2631 mantine-UnstyledButton-root" data-variant="none" type="button" aria-label="Copy code"><span class="m_8d3afb97 mantine-ActionIcon-icon"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" fill="none" stroke-linecap="round" stroke-linejoin="round"><path stroke="none" d="M0 0h24v24H0z" fill="none"></path><path d="M8 8m0 2a2 2 0 0 1 2 -2h8a2 2 0 0 1 2 2v8a2 2 0 0 1 -2 2h-8a2 2 0 0 1 -2 -2z"></path><path d="M16 8v-2a2 2 0 0 0 -2 -2h-8a2 2 0 0 0 -2 2v8a2 2 0 0 0 2 2h2"></path></svg></span></button></div><div style="--scrollarea-scrollbar-size:calc(0.25rem * var(--mantine-scale));--sa-corner-width:0px;--sa-corner-height:0px" class="m_f744fd40 mantine-CodeHighlight-scrollarea m_d57069b5 mantine-ScrollArea-root" dir="ltr"><div style="overflow-x:hidden;overflow-y:hidden;overscroll-behavior-inline:none" class="m_c0783ff9 mantine-ScrollArea-viewport" data-scrollbars="xy"><div class="m_b1336c6 mantine-ScrollArea-content"><pre class="m_2c47c4fd mantine-CodeHighlight-pre" style="padding:0"><code class="m_5caae6d3 mantine-CodeHighlight-code">const homelessUser = {
name: 'Ivan',
age: 29,
};
const result = `${homelessUser.address?.country}, ${homelessUser.address?.city}`;
console.log(result); // => undefined, undefined</code></pre></div></div></div><button class="mantine-focus-auto m_c9378bc2 mantine-CodeHighlight-showCodeButton m_87cf2631 mantine-UnstyledButton-root" data-hidden="true" type="button">Expand code</button></div>
<p>Не смотря на то, что это удобный инструмент, бездумно его использовать не стоит. Обычно его использование говорит о том, что в приложении есть проблемы. Например, в примере выше, должна стоять проверка на существование адреса пользователя. Если адреса нет, то нет смысла составлять строку. Если добавить такую проверку, то необходимость в использовании этого оператора отпадает.</p></div><div class="m_3eebeb36 mantine-Divider-root" data-orientation="horizontal" role="separator"></div><div style="--group-gap:var(--mantine-spacing-md);--group-align:center;--group-justify:flex-start;--group-wrap:wrap;font-size:var(--mantine-font-size-sm)" class="m_4081bf90 mantine-Group-root"><div style="--group-gap:var(--mantine-spacing-xs);--group-align:center;--group-justify:flex-start;--group-wrap:wrap;margin-inline-start:auto" class="m_4081bf90 mantine-Group-root"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.2" stroke-linecap="round" stroke-linejoin="round" class="tabler-icon tabler-icon-calendar "><path d="M4 7a2 2 0 0 1 2 -2h12a2 2 0 0 1 2 2v12a2 2 0 0 1 -2 2h-12a2 2 0 0 1 -2 -2v-12"></path><path d="M16 3v4"></path><path d="M8 3v4"></path><path d="M4 11h16"></path><path d="M11 15h1"></path><path d="M12 15v3"></path></svg><p class="mantine-focus-auto m_b6d8b162 mantine-Text-root" data-inherit="true">4 года назад</p></div><div style="--group-gap:var(--mantine-spacing-xs);--group-align:center;--group-justify:flex-start;--group-wrap:wrap" class="m_4081bf90 mantine-Group-root"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.2" stroke-linecap="round" stroke-linejoin="round" class="tabler-icon tabler-icon-user "><path d="M8 7a4 4 0 1 0 8 0a4 4 0 0 0 -8 0"></path><path d="M6 21v-2a4 4 0 0 1 4 -4h4a4 4 0 0 1 4 4v2"></path></svg><p class="mantine-focus-auto m_b6d8b162 mantine-Text-root" data-inherit="true">Ivan Gagarinov</p></div></div></div></div></div><div style="margin-bottom:var(--mantine-spacing-xl);padding:var(--mantine-spacing-lg)" class="m_e615b15f mantine-Card-root m_1b7284a3 mantine-Paper-root" data-with-border="true" id="answer-2275"><div style="--group-gap:calc(1.125rem * var(--mantine-scale));--group-align:stretch;--group-justify:flex-start;--group-wrap:nowrap" class="m_4081bf90 mantine-Group-root"><div style="--stack-gap:var(--mantine-spacing-md);--stack-align:stretch;--stack-justify:flex-start;font-size:var(--mantine-font-size-h1);font-weight:lighter;text-align:center" class="m_6d731127 mantine-Stack-root">0<a style="color:inherit" class="mantine-focus-auto m_849cf0da m_b6d8b162 mantine-Text-root mantine-Anchor-root" data-underline="hover" href="/qna/javascript/questions/chto-oznachaet-znak-voprosa-v-stroke-comment-author/answers/2275/vote"><div style="--ti-bg:transparent;--ti-color:var(--mantine-color-indigo-light-color);--ti-bd:calc(0.0625rem * var(--mantine-scale)) solid transparent;color:inherit" class="m_7341320d mantine-ThemeIcon-root" data-variant="transparent"><svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="tabler-icon tabler-icon-thumb-up "><path d="M7 11v8a1 1 0 0 1 -1 1h-2a1 1 0 0 1 -1 -1v-7a1 1 0 0 1 1 -1h3a4 4 0 0 0 4 -4v-1a2 2 0 0 1 4 0v5h3a2 2 0 0 1 2 2l-1 5a2 3 0 0 1 -2 2h-7a3 3 0 0 1 -3 -3"></path></svg></div></a></div><div style="--stack-gap:var(--mantine-spacing-md);--stack-align:stretch;--stack-justify:flex-start;width:100%;min-width:0rem" class="m_6d731127 mantine-Stack-root"><div style="margin-bottom:auto" class="m_d08caa0 mantine-Typography-root"><p>Подробнее о том, когда лучше отказаться от использования <code style="margin-bottom:var(--mantine-spacing-lg)" class="m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight m_e597c321 mantine-CodeHighlight-codeHighlight m_dfe9c588 mantine-InlineCodeHighlight-inlineCodeHighlight">?.</code> оператора:</p>
<ol>
<li>
<p>Когда необходимо явно обработать отсутствие значения. Например, если мы ожидаем, что свойство объекта будет иметь определенное значение, и если его нет, то нужно выполнить какие-то дополнительные действия.</p>
</li>
<li>
<p>Когда нужно обеспечить совместимость с более старыми версиями JavaScript. Оператор опциональной последовательности был добавлен в ECMAScript 2020, поэтому его использование может привести к проблемам совместимости с более старыми браузерами или средами выполнения JavaScript.</p>
</li>
<li>
<p>Когда нужно улучшить читаемость кода. Иногда использование оператора опциональной последовательности может усложнить чтение кода, особенно если он содержит множество вложенных свойств и методов.</p>
</li>
</ol></div><div class="m_3eebeb36 mantine-Divider-root" data-orientation="horizontal" role="separator"></div><div style="--group-gap:var(--mantine-spacing-md);--group-align:center;--group-justify:flex-start;--group-wrap:wrap;font-size:var(--mantine-font-size-sm)" class="m_4081bf90 mantine-Group-root"><div style="--group-gap:var(--mantine-spacing-xs);--group-align:center;--group-justify:flex-start;--group-wrap:wrap;margin-inline-start:auto" class="m_4081bf90 mantine-Group-root"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.2" stroke-linecap="round" stroke-linejoin="round" class="tabler-icon tabler-icon-calendar "><path d="M4 7a2 2 0 0 1 2 -2h12a2 2 0 0 1 2 2v12a2 2 0 0 1 -2 2h-12a2 2 0 0 1 -2 -2v-12"></path><path d="M16 3v4"></path><path d="M8 3v4"></path><path d="M4 11h16"></path><path d="M11 15h1"></path><path d="M12 15v3"></path></svg><p class="mantine-focus-auto m_b6d8b162 mantine-Text-root" data-inherit="true">3 года назад</p></div><div style="--group-gap:var(--mantine-spacing-xs);--group-align:center;--group-justify:flex-start;--group-wrap:wrap" class="m_4081bf90 mantine-Group-root"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.2" stroke-linecap="round" stroke-linejoin="round" class="tabler-icon tabler-icon-user "><path d="M8 7a4 4 0 1 0 8 0a4 4 0 0 0 -8 0"></path><path d="M6 21v-2a4 4 0 0 1 4 -4h4a4 4 0 0 1 4 4v2"></path></svg><p class="mantine-focus-auto m_b6d8b162 mantine-Text-root" data-inherit="true">Aleksey</p></div></div></div></div></div><style data-mantine-styles="inline">.__m__-_R_4bbdiub_{--carousel-slide-gap:var(--mantine-spacing-xs);--carousel-slide-size:70%;}@media(min-width: 36em){.__m__-_R_4bbdiub_{--carousel-slide-gap:var(--mantine-spacing-xl);--carousel-slide-size:50%;}}</style><div style="--carousel-control-size:calc(2.5rem * var(--mantine-scale));--carousel-controls-offset:var(--mantine-spacing-sm);margin-top:var(--mantine-spacing-xl);margin-bottom:var(--mantine-spacing-lg);padding-block:var(--mantine-spacing-sm);background:var(--app-color-surface)" class="m_17884d0f mantine-Carousel-root responsiveClassName" data-orientation="horizontal" data-include-gap-in-size="true"><div class="m_39bc3463 mantine-Carousel-controls" data-orientation="horizontal"><button class="mantine-focus-auto m_64f58e10 mantine-Carousel-control m_87cf2631 mantine-UnstyledButton-root" type="button" data-inactive="true" data-type="previous" tabindex="-1"><svg viewBox="0 0 15 15" fill="none" xmlns="http://www.w3.org/2000/svg" style="transform:rotate(90deg);width:calc(1rem * var(--mantine-scale));height:calc(1rem * var(--mantine-scale));display:block"><path d="M3.13523 6.15803C3.3241 5.95657 3.64052 5.94637 3.84197 6.13523L7.5 9.56464L11.158 6.13523C11.3595 5.94637 11.6759 5.95657 11.8648 6.15803C12.0536 6.35949 12.0434 6.67591 11.842 6.86477L7.84197 10.6148C7.64964 10.7951 7.35036 10.7951 7.15803 10.6148L3.15803 6.86477C2.95657 6.67591 2.94637 6.35949 3.13523 6.15803Z" fill="currentColor" fill-rule="evenodd" clip-rule="evenodd"></path></svg></button><button class="mantine-focus-auto m_64f58e10 mantine-Carousel-control m_87cf2631 mantine-UnstyledButton-root" type="button" data-inactive="true" data-type="next" tabindex="-1"><svg viewBox="0 0 15 15" fill="none" xmlns="http://www.w3.org/2000/svg" style="transform:rotate(-90deg);width:calc(1rem * var(--mantine-scale));height:calc(1rem * var(--mantine-scale));display:block"><path d="M3.13523 6.15803C3.3241 5.95657 3.64052 5.94637 3.84197 6.13523L7.5 9.56464L11.158 6.13523C11.3595 5.94637 11.6759 5.95657 11.8648 6.15803C12.0536 6.35949 12.0434 6.67591 11.842 6.86477L7.84197 10.6148C7.64964 10.7951 7.35036 10.7951 7.15803 10.6148L3.15803 6.86477C2.95657 6.67591 2.94637 6.35949 3.13523 6.15803Z" fill="currentColor" fill-rule="evenodd" clip-rule="evenodd"></path></svg></button></div><div class="m_a2dae653 mantine-Carousel-viewport" data-type="media"><div class="m_fcd81474 mantine-Carousel-container __m__-_R_4bbdiub_" data-orientation="horizontal"><div class="m_d98df724 mantine-Carousel-slide" data-orientation="horizontal"><div tabindex="0" style="cursor:pointer;height:100%"><a style="text-decoration:none" class="mantine-focus-auto m_849cf0da m_b6d8b162 mantine-Text-root mantine-Anchor-root" data-underline="hover" href="/programs/typescript?promo_name=programs_list&promo_position=qna_question&promo_creative=catalog_card&promo_type=card" target="_blank"><div style="height:100%" class="m_e615b15f mantine-Card-root m_1b7284a3 mantine-Paper-root" data-with-border="true"><div style="--group-gap:calc(0.25rem * var(--mantine-scale));--group-align:center;--group-justify:flex-start;--group-wrap:nowrap" class="m_4081bf90 mantine-Group-root"><span style="font-size:var(--mantine-font-size-sm)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">2 месяца</span><span class="mantine-focus-auto m_b6d8b162 mantine-Text-root">·</span><span style="font-size:var(--mantine-font-size-sm)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">Для продвинутых</span></div><p style="margin-bottom:var(--mantine-spacing-sm);font-size:var(--mantine-font-size-h5);font-weight:bold" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">Typescript</p><p class="mantine-focus-auto m_b6d8b162 mantine-Text-root">Изучите Typescript и получите навык снижать ошибки, упрощать отладку</p><div style="margin-top:auto" class=""><div class="m_4451eb3a mantine-Center-root"><img style="opacity:0.8;width:70%" class="m_9e117634 mantine-Image-root mantine-visible-from-xs" src="https://hexlet.io/rails/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzcwOSwicHVyIjoiYmxvYl9pZCJ9fQ==--03e50bbd408fef672ad099f7b2a258d80f54ad96/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJ3ZWJwIiwicmVzaXplX3RvX2xpbWl0IjpbNDAwLDQwMF0sInNhdmVyIjp7InF1YWxpdHkiOjg1fX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--5b6f46dacd1af664f27558553a58076185091823/Hand%20coding-bro.png" alt="Typescript" loading="eager"/></div><div style="--group-gap:var(--mantine-spacing-md);--group-align:end;--group-justify:space-between;--group-wrap:wrap;margin-top:var(--mantine-spacing-xs)" class="m_4081bf90 mantine-Group-root"><p style="font-size:var(--mantine-font-size-xl)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">от 3 900 ₽</p><p style="font-size:var(--mantine-font-size-sm)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">Посмотреть →</p></div></div></div></a></div></div><div class="m_d98df724 mantine-Carousel-slide" data-orientation="horizontal"><div tabindex="0" style="cursor:pointer;height:100%"><a style="text-decoration:none" class="mantine-focus-auto m_849cf0da m_b6d8b162 mantine-Text-root mantine-Anchor-root" data-underline="hover" href="/programs/frontend?promo_name=programs_list&promo_position=qna_question&promo_creative=catalog_card&promo_type=card" target="_blank"><div style="height:100%" class="m_e615b15f mantine-Card-root m_1b7284a3 mantine-Paper-root" data-with-border="true"><div style="--group-gap:calc(0.25rem * var(--mantine-scale));--group-align:center;--group-justify:flex-start;--group-wrap:nowrap" class="m_4081bf90 mantine-Group-root"><span style="font-size:var(--mantine-font-size-sm)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">10 месяцев</span><span class="mantine-focus-auto m_b6d8b162 mantine-Text-root">·</span><span style="font-size:var(--mantine-font-size-sm)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">С нуля</span></div><p style="margin-bottom:var(--mantine-spacing-sm);font-size:var(--mantine-font-size-h5);font-weight:bold" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">Фронтенд-разработчик</p><p class="mantine-focus-auto m_b6d8b162 mantine-Text-root">Изучите HTML, CSS, JavaScript и React</p><div style="margin-top:auto" class=""><div class="m_4451eb3a mantine-Center-root"><img style="opacity:0.8;width:70%" class="m_9e117634 mantine-Image-root mantine-visible-from-xs" src="https://hexlet.io/rails/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzcyNywicHVyIjoiYmxvYl9pZCJ9fQ==--2d5cbbf5c3b4a73ae4b2c50632305d78f5872e4d/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJ3ZWJwIiwicmVzaXplX3RvX2xpbWl0IjpbNDAwLDQwMF0sInNhdmVyIjp7InF1YWxpdHkiOjg1fX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--5b6f46dacd1af664f27558553a58076185091823/Programmer-rafiki.png" alt="Фронтенд-разработчик" loading="eager"/></div><div style="--group-gap:var(--mantine-spacing-md);--group-align:end;--group-justify:space-between;--group-wrap:wrap;margin-top:var(--mantine-spacing-xs)" class="m_4081bf90 mantine-Group-root"><p style="font-size:var(--mantine-font-size-xl)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">от 6 792 ₽</p><p style="font-size:var(--mantine-font-size-sm)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">Посмотреть →</p></div></div></div></a></div></div><div class="m_d98df724 mantine-Carousel-slide" data-orientation="horizontal"><div tabindex="0" style="cursor:pointer;height:100%"><a style="text-decoration:none" class="mantine-focus-auto m_849cf0da m_b6d8b162 mantine-Text-root mantine-Anchor-root" data-underline="hover" href="/programs/js-oop?promo_name=programs_list&promo_position=qna_question&promo_creative=catalog_card&promo_type=card" target="_blank"><div style="height:100%" class="m_e615b15f mantine-Card-root m_1b7284a3 mantine-Paper-root" data-with-border="true"><div style="--group-gap:calc(0.25rem * var(--mantine-scale));--group-align:center;--group-justify:flex-start;--group-wrap:nowrap" class="m_4081bf90 mantine-Group-root"><span style="font-size:var(--mantine-font-size-sm)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">2 месяца</span><span class="mantine-focus-auto m_b6d8b162 mantine-Text-root">·</span><span style="font-size:var(--mantine-font-size-sm)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">Для продвинутых</span></div><p style="margin-bottom:var(--mantine-spacing-sm);font-size:var(--mantine-font-size-h5);font-weight:bold" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">ООП на Javascript</p><p class="mantine-focus-auto m_b6d8b162 mantine-Text-root">Изучите архитектуру и принципы чистого кода на JS</p><div style="margin-top:auto" class=""><div class="m_4451eb3a mantine-Center-root"><img style="opacity:0.8;width:70%" class="m_9e117634 mantine-Image-root mantine-visible-from-xs" src="https://hexlet.io/rails/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NDAxOSwicHVyIjoiYmxvYl9pZCJ9fQ==--84efd2b6854b7000046e9ce06e6be85d38af5ab8/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJ3ZWJwIiwicmVzaXplX3RvX2xpbWl0IjpbNDAwLDQwMF0sInNhdmVyIjp7InF1YWxpdHkiOjg1fX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--5b6f46dacd1af664f27558553a58076185091823/JavaScript%20frameworks-cuate.png" alt="ООП на Javascript" loading="eager"/></div><div style="--group-gap:var(--mantine-spacing-md);--group-align:end;--group-justify:space-between;--group-wrap:wrap;margin-top:var(--mantine-spacing-xs)" class="m_4081bf90 mantine-Group-root"><p style="font-size:var(--mantine-font-size-xl)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">от 3 900 ₽</p><p style="font-size:var(--mantine-font-size-sm)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">Посмотреть →</p></div></div></div></a></div></div><div class="m_d98df724 mantine-Carousel-slide" data-orientation="horizontal"><div tabindex="0" style="cursor:pointer;height:100%"><a style="text-decoration:none" class="mantine-focus-auto m_849cf0da m_b6d8b162 mantine-Text-root mantine-Anchor-root" data-underline="hover" href="/programs/js-domain-driven-design?promo_name=programs_list&promo_position=qna_question&promo_creative=catalog_card&promo_type=card" target="_blank"><div style="height:100%" class="m_e615b15f mantine-Card-root m_1b7284a3 mantine-Paper-root" data-with-border="true"><div style="--group-gap:calc(0.25rem * var(--mantine-scale));--group-align:center;--group-justify:flex-start;--group-wrap:nowrap" class="m_4081bf90 mantine-Group-root"><span style="font-size:var(--mantine-font-size-sm)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">2 месяца</span><span class="mantine-focus-auto m_b6d8b162 mantine-Text-root">·</span><span style="font-size:var(--mantine-font-size-sm)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">Для продвинутых</span></div><p style="margin-bottom:var(--mantine-spacing-sm);font-size:var(--mantine-font-size-h5);font-weight:bold" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">DDD на Javascript</p><p class="mantine-focus-auto m_b6d8b162 mantine-Text-root">Изучите ООП и DDD для создания масштабируемого кода</p><div style="margin-top:auto" class=""><div class="m_4451eb3a mantine-Center-root"><img style="opacity:0.8;width:70%" class="m_9e117634 mantine-Image-root mantine-visible-from-xs" src="https://hexlet.io/rails/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NDAwNywicHVyIjoiYmxvYl9pZCJ9fQ==--f0b38f0e25ed59255acec6eaeaeec0a99aec453f/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJ3ZWJwIiwicmVzaXplX3RvX2xpbWl0IjpbNDAwLDQwMF0sInNhdmVyIjp7InF1YWxpdHkiOjg1fX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--5b6f46dacd1af664f27558553a58076185091823/Binary%20code-rafiki.png" alt="DDD на Javascript" loading="eager"/></div><div style="--group-gap:var(--mantine-spacing-md);--group-align:end;--group-justify:space-between;--group-wrap:wrap;margin-top:var(--mantine-spacing-xs)" class="m_4081bf90 mantine-Group-root"><p style="font-size:var(--mantine-font-size-xl)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">от 3 900 ₽</p><p style="font-size:var(--mantine-font-size-sm)" class="mantine-focus-auto m_b6d8b162 mantine-Text-root">Посмотреть →</p></div></div></div></a></div></div><div class="m_d98df724 mantine-Carousel-slide" data-orientation="horizontal"><div tabindex="0" style="cursor:pointer;height:100%"><a style="text-decoration:none" class="mantine-focus-auto m_849cf0da m_b6d8b162 mantine-Text-root mantine-Anchor-root" data-underline="hover" href="/programs/fullstack-javascript?promo_name=programs_list&promo_position=qna_question&promo_creative=catalog_card&promo_type=card" target="_blank"><div style="height:100%" class="m_e615b15f mantine-Card-root m_1b7284a3 mantine-Paper-root" 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