到目前为止，我已经写完了面向对象完整的一个系列知识，前面基本属于理论，原理的理解，接下来，我们就用学到的知识来实战下吧.
看看理解原理和理论是否重要？例子从简单到复杂
一、单体（字面量）封装加减乘除
var Oper = { add : function( n1, n2 ){ return n1 + n2; }, sbb : function( n1, n2 ){ return n1 - n2; }, mul : function( n1, n2 ){ return n1 * n2; }, div : function( n1, n2 ){ return n1 / n2; }, }; console.log( Oper.add( 10, 20 ) ); //30 console.log( Oper.sbb( 10, 20 ) ); //-10 console.log( Oper.mul( 10, 20 ) ); //200 console.log( Oper.div( 10, 20 ) ); //0.5二、构造函数方式
function Oper( n1, n2 ){ this.num1 = n1 || 0; this.num2 = n2 || 0; this.setData = function( n1, n2 ){ this.num1 = n1; this.num2 = n2; }; this.add = function(){ this.setData( arguments[0] || this.num1 || 0, arguments[1] || this.num2 || 0 ); return this.num1 + this.num2; }; this.sbb = function(){ this.setData( arguments[0] || this.num1 || 0, arguments[1] || this.num2 || 0 ); return this.num1 - this.num2; }; this.mul = function(){ this.setData( arguments[0] || this.num1 || 0, arguments[1] || this.num2 || 0 ); return this.num1 * this.num2; }; this.div = function(){ this.setData( arguments[0] || this.num1 || 0, arguments[1] || this.num2 || 0 ); return this.num1 / this.num2; }; }; console.log( new Oper( 10, 20 ).add() ); //30 console.log( new Oper(100, 200).sbb( 10, 20 ) ); //-10 console.log( new Oper().mul( 10, 20 ) ); //200 console.log( new Oper().div( 10, 20 ) ); //0.5三、构造函数+原型对象（prototype）
function Oper(n1, n2) { this.num1 = n1 || 0; this.num2 = n2 || 0; }; Oper.prototype = { constructor : Oper, setData : function (n1, n2) { this.num1 = n1; this.num2 = n2; }, add : function () { this.setData(arguments[0] || this.num1 || 0, arguments[1] || this.num2 || 0); return this.num1 + this.num2; }, sbb : function () { this.setData(arguments[0] || this.num1 || 0, arguments[1] || this.num2 || 0); return this.num1 - this.num2; }, mul : function () { this.setData(arguments[0] || this.num1 || 0, arguments[1] || this.num2 || 0); return this.num1 * this.num2; }, div : function () { this.setData(arguments[0] || this.num1 || 0, arguments[1] || this.num2 || 0); return this.num1 / this.num2; } }; console.log(new Oper().add(10, 20)); //30 console.log(new Oper( 100, 200 ).sbb()); //-100 console.log(new Oper().mul(10, 20)); //200 console.log(new Oper().div(10, 20)); //0.5四、寄生组合继承+简单工厂模式
function Oper( n1, n2 ){ this.num1 = n1; this.num2 = n2; }; Oper.prototype.run = function(){} function object( o ){ var G = function(){}; G.prototype = o; return new G(); }; function inheritPrototype( subObj, superObj ){ var proObj = object( superObj.prototype ); proObj.constructor = subObj; subObj.prototype = proObj; } function OperAdd( n1, n2 ){ Oper.call( this, n1, n2 ); } inheritPrototype( OperAdd, Oper ); OperAdd.prototype.run = function(){ return this.num1 + this.num2; } function OperSbb( n1, n2 ){ Oper.call( this, n1, n2 ); } inheritPrototype( OperSbb, Oper ); OperSbb.prototype.run = function(){ return this.num1 - this.num2; } function OperMul( n1, n2 ){ Oper.call( this, n1, n2 ); } inheritPrototype( OperMul, Oper ); OperMul.prototype.run = function(){ return this.num1 * this.num2; } function OperDiv( n1, n2 ){ Oper.call( this, n1, n2 ); } inheritPrototype( OperDiv, Oper ); OperDiv.prototype.run = function(){ return this.num1 / this.num2; } function OperFactory( oper, n1, n2 ){ switch( oper ) { case ‘+‘: return new OperAdd( n1, n2 ).run(); break; case ‘-‘: return new OperSbb( n1, n2 ).run(); break; case ‘*‘: return new OperMul( n1, n2 ).run(); break; case ‘/‘: return new OperDiv( n1, n2 ).run(); break; } } console.log( OperFactory( ‘+‘, 10, 20 ) ); //30 console.log( OperFactory( ‘-‘, 10, 20 ) ); //-10 console.log( OperFactory( ‘*‘, 10, 20 ) ); //200 console.log( OperFactory( ‘/‘, 10, 20 ) ); //0.5这种方式，虽然增加了代码量， 如果这道题是实际运用，比如说后面还有很多种运算，两个数的乘方，立方，平方等等，
还有其他特殊处理等等，那么这种扩展性就非常强
本文出自 “ghostwu” 博客，请务必保留此出处http://ghostwu.blog.51cto.com/11192807/1962431
[js高手之路]面向对象+设计模式+继承一步步改造简单的四则运算
原文地址：http://ghostwu.blog.51cto.com/11192807/1962431