javascript建立函數的20種方式彙總_javascript技巧

工作上常常會建立一個函數來解決一些需求問題，以下是個人在工作中總結出來的創建函數20種方式，你知道多少？

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

為完成需求，趕緊宣告一個函數吧

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

有求必應，函數表達式來解

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

建立一個方法物件類別看起來比較整潔

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

為單體加入屬性方法，淨化命名空間

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

回傳新物件我們還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();

原型鏈指向防止創建多次

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

物件賦給原型看上去比較整潔

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

別忘了還可以在類別的內部加入屬性

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

基類原型拓展，新的一片空間

 
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();

通用定義方法函數使用更方便

 
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();

原形賦值我們還可以用類別操作

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();

鍊式操作有何不可

 
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();

原型 鍊式=更進一步

 
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();

添加物件一次做得更多

 
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();

原型有什麼不可以

 
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();

函數式新增物件也可以鍊式操作

 
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();

類別的鍊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;
}

函數加入封裝一下

 
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;
}

類式添加追求的就是個人化

 
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();

追求個人化，這麼做不必說為什麼

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