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//第1種寫法
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function Circle(r) {
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this.r = r;
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}
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Circle.PI = 3.14159;
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Circle.prototype.area = function() {
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return Circle.PI * this.r * this.r;
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}
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var c = new Circle(1.0);
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alert(c.area());

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//第2種寫法
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var Circle = function() {
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var obj = new Object();
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obj.PI = 3.14159;
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obj.area = function( r ) {
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return this.PI * r * r;
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}
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return obj;
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}
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var c = new Circle();
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alert( c.area( 1.0 ) );
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//第3種寫法
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var Circle = new Object();
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Circle.PI = 3.14159;
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Circle.Area = function( r ) {
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return this.PI * r * r;
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}
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alert( Circle.Area( 1.0 ) );

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

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