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author | Peter Bengtsson <mail@peterbe.com> | 2020-12-08 14:42:52 -0500 |
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committer | Peter Bengtsson <mail@peterbe.com> | 2020-12-08 14:42:52 -0500 |
commit | 074785cea106179cb3305637055ab0a009ca74f2 (patch) | |
tree | e6ae371cccd642aa2b67f39752a2cdf1fd4eb040 /files/pt-br/web/javascript/reference/global_objects/object/propertyisenumerable/index.html | |
parent | da78a9e329e272dedb2400b79a3bdeebff387d47 (diff) | |
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diff --git a/files/pt-br/web/javascript/reference/global_objects/object/propertyisenumerable/index.html b/files/pt-br/web/javascript/reference/global_objects/object/propertyisenumerable/index.html new file mode 100644 index 0000000000..a68117bc0c --- /dev/null +++ b/files/pt-br/web/javascript/reference/global_objects/object/propertyisenumerable/index.html @@ -0,0 +1,128 @@ +--- +title: Object.prototype.propertyIsEnumerable() +slug: Web/JavaScript/Reference/Global_Objects/Object/propertyIsEnumerable +translation_of: Web/JavaScript/Reference/Global_Objects/Object/propertyIsEnumerable +--- +<div>{{JSRef}}</div> + +<p>O método <code><strong>propertyIsEnumerable()</strong></code> retorna um booleano indicando quando a propriedade especificada é enumerável e é a propriedade do próprio objeto</p> + +<div>{{EmbedInteractiveExample("pages/js/object-prototype-propertyisenumerable.html", "taller")}}</div> + +<p class="hidden">O source deste exemplo interativo é armazenado em um repositório GitHub.Se você deseja contribuir com o projeto de exemplos interativos, vá em:<a href="https://github.com/mdn/interactive-examples">https://github.com/mdn/interactive-examples</a> e nos envie uma solicitação</p> + +<h2 id="Sintaxe">Sintaxe</h2> + +<pre class="syntaxbox notranslate"><code><var>obj</var>.propertyIsEnumerable(<var>prop</var>)</code></pre> + +<h3 id="Parâmetros">Parâmetros</h3> + +<dl> + <dt><code>prop</code></dt> + <dd>O nome da propriedade para teste</dd> +</dl> + +<h3 id="Valor_de_Retorno">Valor de Retorno</h3> + +<p>O {{jsxref("Boolean")}} indicando se a propriedade especificada é enumeravel e é a propriedade do objeto</p> + +<h2 id="Descrição">Descrição</h2> + +<p>Every object has a <code>propertyIsEnumerable</code> method. This method can determine whether the specified property in an object can be enumerated by a {{jsxref("Statements/for...in", "for...in")}} loop, with the exception of properties inherited through the prototype chain. If the object does not have the specified property, this method returns <code>false</code>.</p> + +<h2 id="Exemplos">Exemplos</h2> + +<h3 id="O_uso_basico_de_propertyIsEnumerable">O uso basico de <code>propertyIsEnumerable</code></h3> + +<p>O exemplos a seguir mostram o uso de <code>propertyIsEnumerable</code> em um objeto e um array:</p> + +<pre class="brush: js notranslate">var o = {}; +var a = []; +o.prop = 'is enumerable'; +a[0] = 'is enumerable'; + +o.propertyIsEnumerable('prop'); // returns true +a.propertyIsEnumerable(0); // returns true +</pre> + +<h3 id="Objetos_User-defined_vs._built-in">Objetos User-defined vs. built-in</h3> + +<p>Os exemplos a seguir demostram a enumerabilidade da propriedade user-defined vs. built-in :</p> + +<pre class="brush: js notranslate">var a = ['is enumerable']; + +a.propertyIsEnumerable(0); // returns true +a.propertyIsEnumerable('length'); // returns false + +Math.propertyIsEnumerable('random'); // returns false +this.propertyIsEnumerable('Math'); // returns false +</pre> + +<h3 id="Propriedade_Direct_vs._inherited">Propriedade Direct vs. inherited</h3> + +<pre class="brush: js notranslate">var a = []; +a.propertyIsEnumerable('constructor'); // returns false + +function firstConstructor() { + this.property = 'is not enumerable'; +} + +firstConstructor.prototype.firstMethod = function() {}; + +function secondConstructor() { + this.method = function() { return 'is enumerable'; }; +} + +secondConstructor.prototype = new firstConstructor; +secondConstructor.prototype.constructor = secondConstructor; + +var o = new secondConstructor(); +o.arbitraryProperty = 'is enumerable'; + +o.propertyIsEnumerable('arbitraryProperty'); // returns true +o.propertyIsEnumerable('method'); // returns true +o.propertyIsEnumerable('property'); // returns false + +o.property = 'is enumerable'; + +o.propertyIsEnumerable('property'); // returns true + +// These return false as they are on the prototype which +// propertyIsEnumerable does not consider (even though the last two +// are iteratable with for-in) +o.propertyIsEnumerable('prototype'); // returns false (as of JS 1.8.1/FF3.6) +o.propertyIsEnumerable('constructor'); // returns false +o.propertyIsEnumerable('firstMethod'); // returns false +</pre> + +<h2 id="Especificações">Especificações</h2> + +<table class="standard-table"> + <thead> + <tr> + <th scope="col">Specification</th> + </tr> + </thead> + <tbody> + <tr> + <td>{{SpecName('ESDraft', '#sec-object.prototype.propertyisenumerable', 'Object.prototype.propertyIsEnumerable')}}</td> + </tr> + </tbody> +</table> + +<h2 id="Compatibilidade_com_Navegadores">Compatibilidade com Navegadores</h2> + +<div> + + +<p>{{Compat("javascript.builtins.Object.propertyIsEnumerable")}}</p> +</div> + +<h2 id="Veja_também">Veja também</h2> + +<ul> + <li><a href="/en-US/docs/Web/JavaScript/Enumerability_and_ownership_of_properties">Enumerability and ownership of properties</a></li> + <li>{{jsxref("Statements/for...in", "for...in")}}</li> + <li>{{jsxref("Object.keys()")}}</li> + <li>{{jsxref("Object.defineProperty()")}}</li> +</ul> |