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JavaScript hasOwnProperty() function (picture and text tutorial, with code examples)
JavaScript hasOwnProperty() function (picture and text tutorial, with code examples)
May 21, 2018 pm 03:04 PM
hasOwnProperty() function is used to indicate whether an object itself (excluding the prototype chain) has a property with the specified name. Let’s share with you an example of the JavaScript hasOwnProperty() function through this article. Friends who are interested should take a look
hasOwnProperty() The function is used to indicate an object itself (excluding the prototype chain) Whether there is an attribute with the specified name. If there is, return true, otherwise return false.
This method belongs to the Object object. Since all objects "inherit" the object instance of Object, almost all instance objects can use this method.
Major browsers such as IE 5.5, FireFox, Chrome, Safari, and Opera all support this function.
Syntax
object.hasOwnProperty( propertyName )
Parameters
| Parameters | Description |
|---|---|
| propertyName | String type Specified property name |
返回值
hasOwnProperty()函數(shù)的返回值為Boolean類型。如果對象object具有名稱為propertyName的屬性，則返回true，否則返回false。
此方法不會(huì)檢查對象的原型鏈中是否存在該屬性，該屬性只有是對象本身的一個(gè)成員才會(huì)返回true。
示例&說明
function Site(){
this.name = "CodePlayer";
this.url = "http://www.365mini.com/";
this.sayHello = function(){
document.writeln("歡迎來到" + this.name);
};
}
var obj = {
engine: "PHP"
,sayHi: function(){
document.writeln("歡迎訪問" + this.url);
}
};
// 使用對象obj覆蓋Site本身的prototype屬性
Site.prototype = obj;
var s = new Site();
document.writeln( s.hasOwnProperty("name") ); // true
document.writeln( s.hasOwnProperty("sayHello") ); // true
// 以下屬性繼承自原型鏈，因此為false
document.writeln( s.hasOwnProperty("engine") ); // false
document.writeln( s.hasOwnProperty("sayHi") ); // false
document.writeln( s.hasOwnProperty("toString") ); // false
// 想要查看對象(包括原型鏈)是否具備指定的屬性，可以使用in操作符
document.writeln( "engine" in s ); // true
document.writeln( "sayHi" in s ); // true
document.writeln( "toString" in s ); // true上面是我整理給大家的，希望今后會(huì)對大家有幫助。
相關(guān)文章：
JavaScript isPrototypeOf和hasOwnProperty使用區(qū)別（實(shí)用）
重點(diǎn)講解在JavaScript中的__proto__屬性（圖文教程）
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