JS面向对象5中写法

//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()); //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 ) ); //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 ) ); //第4种写法 var Circle={ "PI":3.14159, "area":function(r){ return this.PI * r * r; } }; alert( Circle.area(1.0) ); //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) );

 

转载于:https://www.cnblogs.com/0515offer/p/4308575.html

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