js 定义函数的几种方法 以及如何调用

/*1.方法调用模式：先定义一个对象，然后在对象的属性中定义方法，通过myobject.property来执行方法，this即指当前的myobject 对象。*/var car = {carId:123,carName:"奥迪",carColor:"red",say:function(){console.log(this.carName+" color is "+this.carColor);}};car.say();/*2.函数调用模式定义一个函数，设置一个变量名保存函数，这时this指向到window对象。*/var mycar = function(name,color){return "my car is " +color+" and "+name ;}console.log(mycar("奥迪","红色"));/*3.构造器调用模式定义一个函数对象，在对象中定义属性，在其原型对象中定义方法。在使用prototype的方法时，必须实例化该对象才能调用其方法。*/var yourcar = function(name,color){this.name = name;this.color = color;};yourcar.prototype ={say:function(){console.log("your car is " +this.name + " and " +this.color);}};var yourcar = new yourcar("奔驰","蓝色");yourcar.say();/*4.apply,call调用模式*/function count(num1, num2) { return num1 + num2; } console.log(count.call(window, 10, 10)); //20 console.log(count.apply(window,[10,20])); //30window.a=100;window.b=300;var myobject={a:40,b:50};var sum = function(){return this.a+this.b;};var sum1 = sum.call(window); // var sum2 = sum.call(myobject);var sum2 = sum.apply(myobject); console.log(sum1+"========="+sum2);// 发现apply()和call()的真正用武之地是能够扩充函数赖以运行的作用域，如果我们想用传统的方法实现window.a=100;window.b=300;var myobject={a:40,b:50};function sum(){console.log(this.a+this.b);}console.log(sum());myobject.sumnumber = sum;console.log(myobject.sumnumber());window.color = "red"; var o = { color: "blue" }; function sayColor(){ console.log(this.color); } sayColor();var OSayColor = sayColor.bind(o); OSayColor(); //blue