prototype

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Shape = Class.create();
Shape.prototype = {
initialize:function(color){
this.color = color;
//alert('in initialize'); 
    },
draw:function(){
alert("in draw");
alert(this.color);
}
}

Circle = Class.create();
Circle.prototype = Object.extend(new Shape(),{
initialize:function(color,radius){
//alert('in Circle initialize'); 
        this.color = color;
this.radius = radius;
},
drawCircle:function(){
alert("in drawCircle");
alert("color:"+this.color);
alert("radius:"+this.radius);
}
})
var circle = new Circle("green", 10);
alert(circle instanceof Shape);
alert(circle instanceof Circle);
var shape = new Shape("red");
alert(shape instanceof Shape);
alert(shape instanceof Circle);

![](http://www.cnblogs.com/images/OutliningIndicators/ContractedBlock.gif)![](http://www.cnblogs.com/images/OutliningIndicators/ExpandedBlockStart.gif)Code
function class1(){
}

class1.prototype = {
m1 : function() {
alert(1);
}
}
function class2(){
}
class2.prototype = class1.prototype;
class2.prototype.method = function(){
alert(2);
}
var obj1 = new class1();
var obj2 = new class2();
obj1.method();
obj2.method();
obj1.m1();
obj2.m1();
class2.prototype.m1 = function() {
alert(3);
}
obj1.m1();
obj2.m1();