call与apply简单介绍

var pet={
    word:'...',
    speak:function(say){
        console.log(say+' '+this.word)
    }
}
//pet.speak('speak')//speak ...
var dog={
    word:'wang'
}
//改变this到dog上
pet.speak.call(dog,'speak')//spaeck wang

function pet1(word){
    this.word=word;
    this.speak=function(){
        console.log(this.word)
    }
}
//类似继承
function dog1(word){
    pet1.call(this,word);
    //pet1.apply(this,arguments)
}
var dog1=new dog1('wang')
dog1.speak()//wang