js37---Function.prototype

Posted 2020-09-19 672530440

    //给函数的prototype新增名字为name，函数体为fn的函数
    
    Function.prototype.method =function(name,fn){
        this.prototype[name] = fn;//this
        return this;
    }
    
    //再扩展Array的方法，新方法的名字，函数体，形参，实参
    
    if(!Array.prototype.forEach){
        //Array.prototype.forEach = function(fn,thisObj){}
        
        //this.fns.forEach(  function(el){el(o);}  ) function(el){el(o)是函数实参
        
        Array.method("forEach",function(fn,thisObj){//forRach是函数名字，后面是函数声明，fn,thisObj是声明里的形参
            var scope = thisObj || window;
            for (var i = 0; i < this.length; i++) {
                fn.call(scope,this[i],i,this);
            }
        })
    }
    if(!Array.prototype.filter){
        //this.fns.filter(function(el){if(el != xxx){return el;}})
        Array.method("filter",function(fn,thisObj){
            var scope = thisObj || window;
            var a = [];
            for (var i = 0; i < array.length; i++) {
                if( !fn.call(scope,this[i],i,this) ){
                    continue;
                }
                a.push(this[i])
            }
            //..........................
            return a;
        })
    }

window.DED = window.DED||{};//有就用自己，没有就用空对象
    DED.util = DED.util || {}
    //观察者
    DED.util.Observer = function(){
        this.fns = []
    }
    //扩展他
    DED.util.Observer.prototype = {
        //观察
        subscribe : function(fn){
            this.fns.push(fn);
        },
        //取消观察
        unsubscribe : function(fn){
            this.fns = this.fns.filter(function(el){
                if(el != fn){
                    return el;
                }
            })
        },
        //循环执行函数被观察的数组
        fire:function(o){
            this.fns.forEach(function(el){
                el(o);
            })
        }
    }

addEvent(items, ‘click‘, function(e) {
          var e = e || window.event;
          var src = e.target || e.srcElement;
          try {
            e.preventDefault();
          }
          catch (ex) {
            e.returnValue = false;
          }

function F(){}
    var f = function(){}
    
    Function.prototype.method =function(name,fn){
        alert(1);
    }
    f.method();//1
    F.method();//1
 

function F(){}
    var f = function(){}
    
    Function.prototype.method =function(name,fn){
        this.prototype[name] = fn;
        return this;
    }
    f.method("a",function(){alert("a");});//1
    F.method("b",function(){alert("b");});//1

    //f.a();//f.a is not a function
    f.prototype.a();//a
    //F.b();//F.b is not a function
    F.prototype.b()//b
    new F().b();//b

 形参看成构造函数传入的成员变量的值。函数名看成类名。this.看成成员属性和成员方法。

 

    function addCar(){
        this.name = 11;
        this.begin = function(){//对象的成员方法属性可以用中括号获取
            alert(1);
        }
    }
    new addCar().begin();//1
    alert(new addCar()["begin"]);//this.begin = function(){alert(1);}
    alert(typeof new addCar()["begin"]);//function
    new addCar()["begin"]();//1
    alert(new addCar()["name"]);//11
    
    var rr = new addCar();
    rr["age"] = 444;
    alert(rr["age"]);//444
    rr["fff"] = function(){alert(777);}
    rr["fff"]();//777