{"json_modified": "2015-04-18T00:35:40.232687", "slug": "Web/JavaScript/Reference/Global_Objects/undefined", "tags": [], "locale": "zh-CN", "title": "undefined", "translations": [{"title": "undefined", "url": "/en-US/docs/Web/JavaScript/Reference/Global_Objects/undefined", "tags": ["JavaScript"], "summary": "The global <code><strong>undefined</strong></code> property represents the primitive value <code><a class=\"glossaryLink\" href=\"/en-US/docs/Glossary/Undefined\" title=\"undefined: A primitive value automatically assigned to variables that have just been declared or to formal arguments for which there are no actual arguments.\">undefined</a></code>. It is one of JavaScript's <a class=\"glossaryLink\" href=\"/en-US/docs/Glossary/Primitive\" title=\"primitive types: A primitive (primitive value, primitive data type) is data that is not an object and has no methods.\">primitive types</a>.", "localization_tags": [], "locale": "en-US", "last_edit": "2015-03-27T02:31:42", "review_tags": []}, {"title": "undefined", "url": "/ja/docs/Web/JavaScript/Reference/Global_Objects/undefined", "tags": ["JavaScript"], "summary": "\u672a\u5b9a\u7fa9\u3067\u3042\u308b\u4e8b\u3092\u610f\u5473\u3059\u308b\u5024\u3002", "localization_tags": ["inprogress"], "locale": "ja", "last_edit": "2015-04-15T00:51:20", "review_tags": []}, {"title": "undefined", "url": "/es/docs/Web/JavaScript/Referencia/Objetos_globales/undefined", "tags": ["JavaScript"], "summary": "El valor undefined.", "localization_tags": [], "locale": "es", "last_edit": "2014-11-19T12:26:22", "review_tags": []}, {"title": "undefined", "url": "/pl/docs/Web/JavaScript/Referencje/W%C5%82asno%C5%9Bci/undefined", "tags": ["Dokumentacja_JavaScript", "JavaScript", "Dokumentacje", "Wszystkie_kategorie"], "summary": "", "localization_tags": [], "locale": "pl", "last_edit": "2014-05-31T00:08:28", "review_tags": []}, {"title": "undefined", "url": "/fr/docs/Web/JavaScript/Reference/Objets_globaux/undefined", "tags": ["R\u00e9f\u00e9rence", "Reference", "R\u00e9ference", "JavaScript"], "summary": "La propri\u00e9t\u00e9 globale <strong><code>undefined</code></strong> repr\u00e9sente la valeur <code>undefined</code><em>.</em> Cette valeur est l'<a href=\"/fr/docs/Web/JavaScript/Structures_de_donn&#xE9;es#Le_type_ind.C3.A9fini\">un des types primitifs de JavaScript</a>.", "localization_tags": [], "locale": "fr", "last_edit": "2015-04-07T13:38:37", "review_tags": []}, {"title": "undefined", "url": "/ru/docs/Web/JavaScript/Reference/Global_Objects/undefined", "tags": ["JavaScript"], "summary": "\u0417\u043d\u0430\u0447\u0435\u043d\u0438\u0435 \u0433\u043b\u043e\u0431\u0430\u043b\u044c\u043d\u043e\u0433\u043e \u0441\u0432\u043e\u0439\u0441\u0442\u0432\u0430 <code><strong>undefined</strong></code> \u043f\u0440\u0435\u0434\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0435 <code>undefined</code>. \u042d\u0442\u043e \u043e\u0434\u043d\u043e \u0438\u0437 <a class=\"glossaryLink\" href=\"/en-US/docs/Glossary/Primitive\" title=\"&#x43F;&#x440;&#x438;&#x43C;&#x438;&#x442;&#x438;&#x432;&#x43D;&#x44B;&#x445; &#x437;&#x43D;&#x430;&#x447;&#x435;&#x43D;&#x438;&#x439;: A primitive (primitive value, primitive data type) is data that is not an Object and does not have any methods.\">\u043f\u0440\u0438\u043c\u0438\u0442\u0438\u0432\u043d\u044b\u0445 \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0439</a> JavaScript.", "localization_tags": [], "locale": "ru", "last_edit": "2014-11-19T12:37:14", "review_tags": []}, {"title": "undefined", "url": "/de/docs/Web/JavaScript/Reference/Global_Objects/undefined", "tags": ["JavaScript"], "summary": "Die globale Eigenschaft <code><strong>undefined</strong></code> repr\u00e4sentiert den Wert <code>undefined</code>. Dieser Wert ist einer der <a class=\"glossaryLink\" href=\"/en-US/docs/Glossary/Primitive\" title=\"primitiven Typen: A primitive (primitive value, primitive data type) is data that is not an Object and does not have any methods.\">primitiven Typen</a> in JavaScript.", "localization_tags": [], "locale": "de", "last_edit": "2015-01-21T01:35:47", "review_tags": []}, {"title": "undefined", "url": "/ca/docs/Web/JavaScript/Referencia/Objectes_standard/undefined", "tags": [], "summary": "El valor de la propietat global <code><strong>undefined</strong></code> representa el valor <code>undefined</code>. \u00c9s un dels <a class=\"glossaryLink\" href=\"/en-US/docs/Glossary/Primitive\" title=\"tipus primitius: A primitive (primitive value, primitive data type) is data that is not an Object and does not have any methods.\">tipus primitius</a> de JavaScript.", "localization_tags": [], "locale": "ca", "last_edit": "2015-02-12T17:01:35", "review_tags": ["editorial"]}, {"title": "undefined", "url": "/pt-BR/docs/Web/JavaScript/Reference/Global_Objects/undefined", "tags": [], "summary": "O valor global <code>undefined</code> representa um valor indefinido. Trata-se de um dos\u00a0<a class=\"glossaryLink\" href=\"/pt-BR/docs/Glossario/Primitivo\" title=\"tipos primitivos: Um&#xA0;primitivo&#xA0;(valor primitivo, tipo de dados primitivo) &#xE9; um dado que n&#xE3;o &#xE9; representado atrav&#xE9;s de um&#xA0;Objeto e, por consequ&#xEA;ncia, n&#xE3;o possui m&#xE9;todos.\">tipos primitivos</a> do JavaScript.", "localization_tags": [], "locale": "pt-BR", "last_edit": "2015-02-15T15:36:33", "review_tags": []}, {"title": "undefined", "url": "/it/docs/Web/JavaScript/Reference/Global_Objects/undefined", "tags": [], "summary": "La variabile globale\u00a0<strong><code>undefined</code></strong>\u00a0rappresenta il valore primitivo\u00a0<span style=\"font-family: Consolas, Monaco, 'Andale Mono', monospace;\"><a class=\"glossaryLink\" href=\"/en-US/docs/Glossary/Undefined\" title=\"undefined: A primitive value automatically assigned to variables that have just been declared or to formal arguments for which there are no actual arguments.\">undefined</a></span>.\u00a0\u00c8 uno dei <a class=\"glossaryLink\" href=\"/en-US/docs/Glossary/Primitive\" title=\"valori primitivi: A primitive (primitive value, primitive data type) is data that is not an object and has no methods.\">valori primitivi</a> di JavaScript.", "localization_tags": [], "locale": "it", "last_edit": "2015-04-12T06:23:10", "review_tags": []}], "modified": "2015-04-18T00:35:37", "label": "undefined", "localization_tags": [], "url": "/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/undefined", "last_edit": "2015-04-18T00:35:31", "summary": "<code>undefined</code>\u6709\u591a\u91cd\u89d2\u8272,\u901a\u5e38\u60c5\u51b5\u4e0b,\u6211\u4eec\u6240\u8bf4\u7684<code>undefined</code>\u90fd\u6307\u7684\u662f\u5168\u5c40\u5bf9\u8c61\u7684\u4e00\u4e2a\u5c5e\u6027<code>\"undefined\"</code>.", "sections": [{"id": "Quick_Links", "title": "JavaScript \u6559\u7a0b: JavaScript \u6307\u5357 Introduction Grammar and types Control flow and error handling Loops and iteration Functions Expressions and operators Numbers and dates Text formatting Regular expressions Indexed collections Keyed collections Working with objects Details of the object model Iterators and generators Meta programming \u5feb\u901f\u5165\u95e8 JavaScript \u57fa\u7840\u77e5\u8bc6 JavaScript \u77e5\u8bc6\u6982\u8981 Javascript \u9762\u5411\u5bf9\u8c61\u7f16\u7a0b \u4e2d\u7ea7\u6559\u7a0b \u6df1\u5165 JavaScript JavaScript \u6570\u636e\u7ed3\u6784 \u5982\u4f55\u6b63\u786e\u5224\u65ad\u76f8\u7b49\u6027 Closures \u9ad8\u7ea7 \u7ee7\u627f\u548c\u539f\u578b\u94fe \u4e25\u683c\u6a21\u5f0f JavaScript \u7c7b\u578b\u5316\u6570\u7ec4 \u5185\u5b58\u7ba1\u7406 Concurrency model and Event Loop \u5f15\u7528: \u5185\u7f6e\u5bf9\u8c61 JavaScript \u6807\u51c6\u5e93 Array ArrayBuffer Boolean DataView [Translate] Date Error EvalError Float32Array [Translate] Float64Array [Translate] Function Generator [Translate] GeneratorFunction [Translate] Infinity Int16Array [Translate] Int32Array [Translate] Int8Array [Translate] InternalError [Translate] Intl [Translate] Intl.Collator [Translate] Intl.DateTimeFormat [Translate] Intl.NumberFormat [Translate] Iterator [Translate] JSON Map Math NaN Number Object ParallelArray Promise Proxy RangeError [Translate] ReferenceError [Translate] Reflect [Translate] RegExp Set StopIteration [Translate] String Symbol SyntaxError TypeError [Translate] TypedArray URIError [Translate] Uint16Array [Translate] Uint32Array Uint8Array [Translate] Uint8ClampedArray [Translate] WeakMap WeakSet decodeURI decodeURIComponent() encodeURI() encodeURIComponent() escape() eval() isFinite() isNaN() null parseFloat parseInt undefined unescape() [Translate] uneval() [Translate] \u8868\u8fbe\u5f0f\u548c\u8fd0\u7b97\u7b26 \u8fd0\u7b97\u7b26 \u7b97\u672f\u8fd0\u7b97\u7b26 \u6570\u7ec4\u63a8\u5bfc\u5f0f \u8d4b\u503c\u8fd0\u7b97\u7b26 \u6309\u4f4d\u64cd\u4f5c\u7b26 \u9017\u53f7\u64cd\u4f5c\u7b26 Comparison operators [Translate] Conditional (ternary) Operator [Translate] \u89e3\u6784\u8d4b\u503c\uff08Destructuring assignment\uff09 Expression closures [Translate] Generator comprehensions [Translate] \u5706\u62ec\u53f7\u8fd0\u7b97\u7b26 Legacy generator function expression [Translate] \u903b\u8f91\u8fd0\u7b97\u7b26 Object initializer [Translate] \u8fd0\u7b97\u7b26\u4f18\u5148\u7ea7 Property accessors [Translate] \u5c55\u5f00\u8fd0\u7b97\u7b26 class expression [Translate] delete \u51fd\u6570\u8868\u8fbe\u5f0f function* expression [Translate] in instanceof new\u8fd0\u7b97\u7b26 super this typeof void \u8fd0\u7b97\u7b26 yield yield* \u8bed\u53e5\u548c\u58f0\u660e Statements Legacy generator function [Translate] block break class [Translate] const continue debugger do...while empty export [Translate] for [Translate] for each...in for...in for...of function \u751f\u6210\u5668\uff08generator\uff09 if...else import [Translate] label let return switch throw try...catch [Translate] var while with \u51fd\u6570 \u51fd\u6570\u548c\u51fd\u6570\u4f5c\u7528\u57df arguments \u7bad\u5934\u51fd\u6570 \u9ed8\u8ba4\u53c2\u6570\u503c \u65b9\u6cd5\u7684\u5b9a\u4e49 \u5269\u4f59\u53c2\u6570 getter setter Classes Classes [Translate] constructor [Translate] extends [Translate] static [Translate] \u66f4\u591a \u8bcd\u6cd5\u6587\u6cd5 JavaScript \u6570\u636e\u7ed3\u6784 \u5c5e\u6027\u7684\u53ef\u679a\u4e3e\u6027\u548c\u6240\u6709\u6743 Iteration protocols \u4e25\u683c\u6a21\u5f0f \u5207\u6362\u5230\u4e25\u683c\u6a21\u5f0f \u6a21\u677f\u5b57\u7b26\u4e32 \u5df2\u5e9f\u5f03\u7684\u7279\u6027 New in JavaScript New in JavaScript Mozilla\u5bf9ECMAScript 5\u7684\u652f\u6301 Firefox \u4e2d ECMAScript 6 \u7684\u5b9e\u73b0\u60c5\u51b5 ECMAScript 7 support in Mozilla [Translate] Firefox JavaScript changelog [Translate] New in JavaScript 1.1 [Translate] New in JavaScript 1.2 [Translate] New in JavaScript 1.3 [Translate] New in JavaScript 1.4 [Translate] JavaScript 1.5 \u7684\u65b0\u7279\u6027 JavaScript 1.6 \u7684\u65b0\u7279\u6027 New in JavaScript 1.7 New in JavaScript 1.8 New in JavaScript 1.8.1 [Translate] JavaScript 1.8.5 \u7684\u65b0\u7279\u6027 \u6587\u6863: \u5e38\u7528\u5217\u8868 \u5168\u90e8\u9875\u9762\u7d22\u5f15 \u65b9\u6cd5\u7d22\u5f15 \u5c5e\u6027\u7d22\u5f15 \u62e5\u6709 \"JavaScript\" \u6807\u7b7e\u7684\u9875\u9762 \u8d21\u732e JavaScript \u6587\u6863\u7ffb\u8bd1\u72b6\u6001 MDN \u9879\u76ee"}, {"id": "Summary", "title": "\u6982\u8ff0"}, {"id": "Syntax", "title": "\u8bed\u6cd5"}, {"id": "Description", "title": "\u63cf\u8ff0"}], "id": 59401, "review_tags": []}