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• 句法
• 描述
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

call() method calls a function with a given this value and arguments provided individually.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

句法

func.call([thisArg[, arg1, arg2, ...argN]])
					

参数

thisArg 可选

The value to use as this when calling func .

Caution: In certain cases, thisArg may not be the actual value seen by the method.

If the method is a function in non-strict mode , null and undefined will be replaced with the global object, and primitive values will be converted to objects.

arg1 , arg2 , ... argN 可选

Arguments for the function.

返回值

The result of calling the function with the specified this value and arguments.

描述

call() allows for a function/method belonging to one object to be assigned and called for a different object.

call() provides a new value of this to the function/method. With call() , you can write a method once and then inherit it in another object, without having to rewrite the method for the new object.

注意： While the syntax of this function is almost identical to that of apply() , the fundamental difference is that call() accepts an argument list ，而 apply() accepts a single array of arguments .

范例

使用 call to chain constructors for an object

可以使用 call to chain constructors for an object (similar to Java).

In the following example, the constructor for the Product object is defined with two parameters: name and price .

Two other functions, Food and Toy , invoke Product , passing this , name ，和 price . Product initializes the properties name and price , both specialized functions define the category .

function Product(name, price) {
  this.name = name;
  this.price = price;
}
function Food(name, price) {
  Product.call(this, name, price);
  this.category = 'food';
}
function Toy(name, price) {
  Product.call(this, name, price);
  this.category = 'toy';
}
const cheese = new Food('feta', 5);
const fun = new Toy('robot', 40);
					

使用 call to invoke an anonymous function

In this example, we create an anonymous function and use call to invoke it on every object in an array.

The main purpose of the anonymous function here is to add a print function to every object, which is able to print the correct index of the object in the array.

Passing the object as this value is not strictly necessary, but is done for explanatory purpose.

const animals = [
  { species: 'Lion', name: 'King' },
  { species: 'Whale', name: 'Fail' }
];
for (let i = 0; i < animals.length; i++) {
  (function(i) {
    this.print = function() {
      console.log('#' + i + ' ' + this.species
                  + ': ' + this.name);
    }
    this.print();
  }).call(animals[i], i);
}
					

使用 call to invoke a function and specifying the context for ' this '

In the example below, when we call greet , the value of this will be bound to object obj .

function greet() {
  const reply = [this.animal, 'typically sleep between', this.sleepDuration].join(' ');
  console.log(reply);
}
const obj = {
  animal: 'cats', sleepDuration: '12 and 16 hours'
};
greet.call(obj);  // cats typically sleep between 12 and 16 hours
					

使用 call to invoke a function and without specifying the first argument

In the example below, we invoke the display function without passing the first argument. If the first argument is not passed, the value of this is bound to the global object.

var sData = 'Wisen';
function display() {
  console.log('sData value is %s ', this.sData);
}
display.call();  // sData value is Wisen
					

Caution: In strict mode, the value of this will be undefined . See below.

'use strict';
var sData = 'Wisen';
function display() {
  console.log('sData value is %s ', this.sData);
}
display.call(); // Cannot read the property of 'sData' of undefined
					

规范

规范
ECMAScript (ECMA-262) The definition of 'Function.prototype.call' in that specification.

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
call	Chrome 1	Edge 12	Firefox 1	IE 5.5	Opera 4	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs Yes

图例

完整支持

完整支持

另请参阅

• Function.prototype.bind()
• Function.prototype.apply()

• Introduction to Object-Oriented JavaScript

元数据

• 最后修改： May 8, 2020

相关话题

1. 标准内置对象
2. Function
3. 特性
   1. Function.arguments
   2. Function.caller
   3. Function.displayName
   4. Function.length
   5. Function.name
4. 方法
   1. Function.prototype.apply()
   2. Function.prototype.bind()
   3. Function.prototype.call()
   4. Function.prototype.toSource()
   5. Function.prototype.toString()
5. 继承：
6. Object
7. 特性
   1. Object.prototype.__proto__
   2. Object.prototype.constructor
8. 方法
   1. Object.prototype.__defineGetter__()
   2. Object.prototype.__defineSetter__()
   3. Object.prototype.__lookupGetter__()
   4. Object.prototype.__lookupSetter__()
   5. Object.prototype.hasOwnProperty()
   6. Object.prototype.isPrototypeOf()
   7. Object.prototype.propertyIsEnumerable()
   8. Object.prototype.toLocaleString()
   9. Object.prototype.toSource()
   10. Object.prototype.toString()
   11. Object.prototype.valueOf()
   12. Object.setPrototypeOf()