javascript创建函数的20种方式汇总

工作中常常会创建一个函数来解决一些需求问题，以下是个人在工作中总结出来的创建函数20种方式，你知道多少？

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

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();

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();

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();

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();

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();

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();

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();

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();

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();

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();

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();

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();

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();

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();

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();

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();

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;
}

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;
}

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();

追求个性化，这么做不必说为什么

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