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
