javascript创建函数的20种方式汇总

1.函数声明

function sayHello(){
    console.log('hello');
}
function leave(){
    console.log('goodbye');
}
//test
sayHello();

2.为完成需求，赶紧声明一个函数吧

var sayHello = function(){
    console.log('hello');
}
var leave = function(){
    console.log('goodbye');
}
//test
leave();

3.有求必应，函数表达数来解决

var Action = {
    sayHello : function(){
        console.log('hello');
    },
    leave : function(){
        console.log('goodbye');
    }
}
//test
Action.sayHello();

4.创建一个方法对象类看起来更整洁

var Action = function(){};
Action.sayHello = function(){
    console.log('hello');
}
Action.leave = function(){
    console.log('goodbye');
}
//test
Action.sayHello();

5.为单体添加属性方法，净化命名空间

var Action = function(){
    return {
        sayHello : function(){
            console.log('hello');
        },
        leave : function(){
            console.log('goodbye');
        }
    }
}
// //test
var a = Action();
a.leave();

6.返回新对象我们还有更多的事情可以做

var Action = function(){};
Action.prototype.sayHello = function(){
    console.log('hello');
}
Action.prototype.leave = function(){
    console.log('goodbye');
}
//test
var a = new Action();
a.sayHello();

7.原型链指向防止创建多次

var Action = function(){};
Action.prototype = {
    sayHello : function(){
        console.log('hello');
    },
    leave : function(){
        console.log('goodbye');
    }
}
//test
var a = new Action();
a.leave();

8.对象赋给原型看上去更整洁

var Action = function(){
    this.sayHello = function(){
        console.log('hello');
    }
    this.leave = function(){
        console.log('goodbye');
    }
}
//test
var a = new Action();
a.leave();

9.别忘了还可以在类的内部添加属性

Function.prototype.sayHello = function(){
    console.log('hello');
}
Function.prototype.leave = function(){
    console.log('leave');
}
//test
var f = function(){};
f.sayHello();

10.基类原型拓展，新的一片空间

Function.prototype.addMethod = function(name, fn){
    this[name] = fn;
}
var methods = function(){};
methods.addMethod('sayHello', function(){
    console.log('hello');
});
methods.addMethod('leave', function(){
    console.log('leave');
});
//test
methods.sayHello();

11.通用定义方法函数使用更方便

Function.prototype.addMethod = function(name, fn){
    this.prototype[name] = fn;
}
var Methods = function(){};
Methods.addMethod('sayHello', function(){
    console.log('hello');
});
Methods.addMethod('leave', function(){
    console.log('leave');
});
//test
var a = new Methods();
a.leave();

12.原形赋值我们还可以用类操作

Function.prototype.addMethod = function(name, fn){
    this[name] = fn;
    return this;
}
var methods = function(){};
methods.addMethod('sayHello', function(){
    console.log('hello');
}).addMethod('leave', function(){
    console.log('leave');
});
//test
methods.leave();

13.链式操作有何不可

Function.prototype.addMethod = function(name, fn){
    this.prototype[name] = fn;
    return this;
}
var Methods = function(){};
Methods.addMethod('sayHello', function(){
    console.log('hello');
}).addMethod('leave', function(){
    console.log('leave');
});
//test
var a = new Methods();
a.leave();

14.原型+链式=更进一步

Function.prototype.addMethod = function(obj){
    for(var key in obj){
        this[key] = obj[key];
    }
}
var methods = function(){};
methods.addMethod({
    sayHello : function(){
        console.log('hello');
    },
    leave : function(){
        console.log('goodbye');
    }
});
//test
methods.leave();

15.添加对象一次做得更多

Function.prototype.addMethod = function(obj){
    for(var key in obj){
        this.prototype[key] = obj[key];
    }
}
var Methods = function(){};
Methods.addMethod({
    sayHello : function(){
        console.log('hello');
    },
    leave : function(){
        console.log('goodbye');
    }
});
//test
var a = new Methods();
a.leave();

16.原型有什么不可以

Function.prototype.addMethod = function(obj){
    for(var key in obj){
        this[key] = obj[key];
    }
    return this;
}
var methods = function(){};
methods.addMethod({
    sayHello : function(){
        console.log('hello');
    }
}).addMethod({
    leave : function(){
        console.log('goodbye');
    }
});
//test
methods.leave();

17.函数式添加对象也可以链式操作

Function.prototype.addMethod = function(obj){
    for(var key in obj){
        this.prototype[key] = obj[key];
    }
    return this;
}
var Methods = function(){};
Methods.addMethod({
    sayHello : function(){
        console.log('hello');
    }
}).addMethod({
    leave : function(){
        console.log('goodbye');
    }
});
//test
var a = new Methods();
a.leave();

18.类的链式操作也可以做得更多

Function.prototype.addMethod = function(){
    if(arguments.length < 1)
        return;
    var tostring = Object.prototype.toString;
    if(tostring.call(arguments[0]) === '[object Object]'){
        for(var key in arguments[0]){
            this[key] = arguments[0][key];
        }
    }else if(typeof arguments[0] === "string" && tostring.call(arguments[1]) === '[object Function]'){
        this[arguments[0]] = arguments[1];
    }
    return this;
}

19.函数添加封装一下

Function.prototype.addMethod = function(){
    if(arguments.length < 1)
        return;
    var tostring = Object.prototype.toString;
    if(tostring.call(arguments[0]) === '[object Object]'){
        for(var key in arguments[0]){
            this.prototype[key] = arguments[0][key];
        }
    }else if(typeof arguments[0] === "string" && tostring.call(arguments[1]) === '[object Function]'){
        this.prototype[arguments[0]] = arguments[1];
    }
    return this;
}

20.类式添加追求的就是个性化

Function.prototype.addMethod = function(){
    if(arguments.length < 1)
        return;
    var cout = 0,
        tostring = Object.prototype.toString,
        that;
    if(typeof arguments[0] === "boolean" && arguments[0]){
        cout++;
        that = this;
    }else{
        that = this.prototype;
    }
    if(tostring.call(arguments[cout]) === '[object Object]'){
        for(var key in arguments[cout]){
            that[key] = arguments[cout][key];
        }
    }else if(typeof arguments[cout] === "string" && tostring.call(arguments[cout + 1]) === '[object Function]'){
        that[arguments[cout]] = arguments[cout + 1];
    }
    return this;
}
//text
var Text1 = function(){};
Text1
.addMethod('sayHello', function(){console.log('last say hello!')})
.addMethod('leave', function(){console.log('last goodbye!')});
var t = new Text1();
t.sayHello();
t.leave();
var test2 = function(){};
test2
.addMethod(true, 'sayHello', function(){console.log('last say hello!')})
.addMethod(true, 'leave', function(){console.log('last goodbye!')});
test2.sayHello();
test2.leave();