标签：
4种。
1.function circleArea(r) {
this.r = r;
this.area = function() {
console.log(‘第一种：‘+Math.PI * this.r * this.r) ;
};
}
//测试
var ct= new circleArea(1.5);
ct.area();
2.function circleArea(r){ this.r = r; } circleArea.prototype.area = function () { console.log(‘第二种：‘+Math.PI * this.r * this.r) ; }; //测试 var ct = new circleArea(2.5); ct.area();
3.var circleArea = { r : 1, area : function() { console.log(‘第三种：‘+Math.PI*this.r*this.r) } }; //测试 circleArea.r = 6; circleArea.area();
4.var circleArea = {}; circleArea.r = 5; circleArea.area = function() { console.log(‘第四种：‘+Math.PI*this.r*this.r); }; //测试 circleArea.area();
标签：
原文地址：http://www.cnblogs.com/camillea/p/js_oobway.html
