明月松間照 清泉石上流

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對象創(chuàng)建：
var Acircle = {
?pi : Math.PI,
?getCircleArea: function(x,y,r) {
??return this.pi*r*r;
?}
}

上述與以下代碼相同：
function Circle(xPoint,yPoint,radius) {
?this.x = xPoint;
?this.y = yPoint;
?this.r = radius;
}

Circle.prototype.pi = Math.PI;
function Circle.prototype.area() {
?return this.pi*this.r*this.r;
}
//Circle.prototype.area = circleArea;

function getCircleArea(x,y,r) {
?aCircle = new Circle(x,y,r);
?return aCircle.area();
}

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var Try = {
? these: function() {
??? var returnValue;

??? for (var i = 0; i < arguments.length; i++) {
????? var lambda = arguments[i];
????? try {
??????? returnValue = lambda();
??????? break;
????? } catch (e) {}
??? }

??? return returnValue;
? }
}

var Ajax = {
? getTransport: function() {
??? return Try.these(
????? function() {return new ActiveXObject('Msxml2.XMLHTTP')},
????? function() {return new ActiveXObject('Microsoft.XMLHTTP')},
????? function() {return new XMLHttpRequest()}
??? ) || false;
? },

? activeRequestCount: 0
}

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用原型方法（用prototype定義）在大量定義對象的時候會比較節(jié)省資源。也可以在系統(tǒng)的類(如String)上面附加新的方法。
function String.prototype.trim()
?{
?return? this.replace(/(^\s*)|(\s*$)/g, "");
?}
alert("? abcd? ".trim());