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])); //30

window.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