通话和申请有什么区别? [英] What is the difference between call and apply?
问题描述
使用 call
和 apply
来调用函数有什么区别?
var func = function(){
alert('hello!');
};
func.apply();
p>
vs
func.call();
这两种方法之间是否存在性能差异?何时最好使用调用
超过 apply
,反之亦然?
arguments
作为一个数组; call
要求显式列出参数。一个有用的助记符是 a rray和 C 用于 c omma的 A 。 伪语法:
$ b $ theFunction.apply(valueForThis,arrayOfArgs)
theFunction.call(valueForThis,arg1,arg2,...)
ES6还有可能 spread
用于调用
函数的数组,您可以看到兼容性此处。
桑普le code:
function theFunction(name,profession){console.log 我的名字是+ name +,我是+职业+。);} theFunction(John,fireman); theFunction.apply(undefined,[Susan,school teacher] ); theFunction.call(undefined,Claude,mathematician); theFunction.call(undefined,... [Matthew,物理学家]); //与扩展运算符一起使用
What is the difference between using call
and apply
to invoke a function?
var func = function(){
alert('hello!');
};
func.apply();
vs
func.call();
Are there performance differences between the two methods? When is it best to use call
over apply
and vice versa?
The difference is that apply
lets you invoke the function with arguments
as an array; call
requires the parameters be listed explicitly. A useful mnemonic is "A for array and C for comma."
See MDN's documentation on apply and call.
Pseudo syntax:
theFunction.apply(valueForThis, arrayOfArgs)
theFunction.call(valueForThis, arg1, arg2, ...)
There is also, as of ES6, the possibility to spread
the array for use with the call
function, you can see the compatibilities here.
Sample code:
function theFunction(name, profession) {
console.log("My name is " + name + " and I am a " + profession +".");
}
theFunction("John", "fireman");
theFunction.apply(undefined, ["Susan", "school teacher"]);
theFunction.call(undefined, "Claude", "mathematician");
theFunction.call(undefined, ...["Matthew", "physicist"]); // used with the spread operator
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