From 074785cea106179cb3305637055ab0a009ca74f2 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:42:52 -0500 Subject: initial commit --- .../global_objects/symbol/hasinstance/index.html | 114 +++++++++++++++++++++ 1 file changed, 114 insertions(+) create mode 100644 files/pt-br/web/javascript/reference/global_objects/symbol/hasinstance/index.html (limited to 'files/pt-br/web/javascript/reference/global_objects/symbol/hasinstance') diff --git a/files/pt-br/web/javascript/reference/global_objects/symbol/hasinstance/index.html b/files/pt-br/web/javascript/reference/global_objects/symbol/hasinstance/index.html new file mode 100644 index 0000000000..b40b57a3c4 --- /dev/null +++ b/files/pt-br/web/javascript/reference/global_objects/symbol/hasinstance/index.html @@ -0,0 +1,114 @@ +--- +title: Symbol.hasInstance +slug: Web/JavaScript/Reference/Global_Objects/Symbol/hasInstance +tags: + - Propriedade + - Referencia +translation_of: Web/JavaScript/Reference/Global_Objects/Symbol/hasInstance +--- +
{{JSRef}}
+ +

O symbol bem-conhecido Symbol.hasInstance é usado para determinar se um objeto construtor reconhece um objeto como de sua instância. O comportamento do operador {{jsxref("Operators/instanceof", "instanceof")}} pode ser customizado por este symbol.

+ +
{{js_property_attributes(0,0,0)}}
+ +

Exemplos

+ +

Você pode implementar o comportamento customizado do seu instanceof deste jeito; por exemplo:

+ +
class MyArray {
+  static [Symbol.hasInstance](instance) {
+    return this.prototype.isPrototypeOf(instance) ||
+           Array.isArray(instance);
+  }
+}
+
+console.log([] instanceof MyArray); // true
+console.log(new MyArray instanceof MyArray); // true
+console.log(new Image instanceof MyArray); // false
+
+class MySubArray extends MyArray {}
+console.log(new MySubArray instanceof MySubArray); // true
+console.log(new MySubArray instanceof MyArray); // true
+console.log(new MyArray instanceof MySubArray); // false
+ +

Especificações

+ + + + + + + + + + + + + + + + + + + +
SpecificationStatusComment
{{SpecName('ES6', '#sec-symbol.hasinstance', 'Symbol.hasInstance')}}{{Spec2('ES6')}}Initial definition.
{{SpecName('ESDraft', '#sec-symbol.hasinstance', 'Symbol.hasInstance')}}{{Spec2('ESDraft')}} 
+ +

Compatibilidade com os navegadores

+ +

{{CompatibilityTable}}

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+ + + + + + + + + + + + + + + + + + + +
FeatureChromeFirefox (Gecko)Internet ExplorerOperaSafari
Basic support{{CompatChrome(51)}}{{ CompatGeckoDesktop(50) }}{{CompatNo}}{{CompatUnknown}}{{CompatUnknown}}
+
+ +
+ + + + + + + + + + + + + + + + + + + + + +
FeatureAndroidChrome for AndroidFirefox Mobile (Gecko)IE MobileOpera MobileSafari Mobile
Basic support{{CompatUnknown}}{{CompatUnknown}}{{ CompatGeckoMobile(50) }}{{CompatNo}}{{CompatUnknown}}{{CompatUnknown}}
+
+ +

Veja também

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