2019独角兽企业重金招聘Python工程师标准>>> 
//定义Circle类，拥有成员变量r，常量PI和计算面积的成员函数area()
- //第1种写法
- function Circle(r) {
- this.r = r;
- }
- Circle.PI = 3.14159;
- Circle.prototype.area = function() {
- return Circle.PI * this.r * this.r;
- }
- var c = new Circle(1.0);
- alert(c.area());
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- //第2种写法
- var Circle = function() {
- var obj = new Object();
- obj.PI = 3.14159;
- obj.area = function( r ) {
- return this.PI * r * r;
- }
- return obj;
- }
- var c = new Circle();
- alert( c.area( 1.0 ) );
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- //第3种写法
- var Circle = new Object();
- Circle.PI = 3.14159;
- Circle.Area = function( r ) {
- return this.PI * r * r;
- }
- alert( Circle.Area( 1.0 ) );
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- //第4种写法
- var Circle={
- "PI":3.14159,
- "area":function(r){
- return this.PI * r * r;
- }
- };
- alert( Circle.area(1.0) );
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- //第5种写法
- var Circle = new Function("this.PI = 3.14159;this.area = function( r ) {return r*r*this.PI;}");
- alert( (new Circle()).area(1.0) );