js中的call()与apply()

js中的call()函数和apply()函数的作用是用于指定作用域和传参

用于传参，请看以下代码：

<script type="text/javascript">function sum(num1,num2){    return num1 + num2;}function callSum1(num1,num2){    return sum.apply(this,arguments);}function callSum2(num1,num2){    return sum.apply(this,[num1,num2]);}console.log(callSum1(10,10));//20console.log(callSum2(10,10));//20function callSum3(num1,num2){    return sum.call(this,num1,num2);}console.log(callSum3(10,10));//20</script>

用于指定作用域：

<script type="text/javascript">window.color = "red";var o = {color:"blue"};function sayColor(){    console.log(this.color);    }sayColor.call(this);sayColor.call(window);sayColor.call(o);</script>