JavaScript Function.apply() 函数详解

function test(){     
console.log(this)
 };
test()//运行时this指向window

 var obj = {name: "李四", age: 20}; 
test.call(obj)//这样也算是以call指定完上下文再运行，此时this指向obj

 

https://www.cnblogs.com/1175429393wljblog/p/4538394.html