js中call和apply的用法

call的用方法： 

var obj = {
     arg1: 1,
     arg2: 2
}
function f(a,b){
     return this.arg1 + this.arg2 + a + b;
}

var r = f.call(obj,3,4);  // r =10

等同于： 

 var obj = {
     arg1: 1,
     arg2: 2
}


function f(a,b){
     return this.arg1 + this.arg2 + a + b;
}


obj.m = f;
var r = obj.m(3,4);
delete obj.m;

applay和call方法相似，只不过要传递的参数以数组的形式制定上面的代码调用apply可写成： 

var obj = {
     arg1: 1,
     arg2: 2
}
function f(a,b){
     return this.arg1 + this.arg2 + a + b;
}

var r = f.apply(obj,[3,4]);  // r =10