JavaScript摘要

1 采用匿名自执行函数定义对象

var Size = (function size() {

    function constructor(w, h) {

        this.w = w;

        this.h = h;

    }

    constructor.prototype = {

        toString: function () {

            return "(" + this.w + ", " + this.h + ")";

        },

        getHalfSize: function () {

            return new Size(this.w >>> 1, this.h >>> 1);

        },

        length: function () {

            return this.w * this.h;

        }

    };

    return constructor;

})();

此写法表示在该代码解释时就自动会执行（function size())中的方法

目的，避免污染外部的变量

2 get set访问器

var log = ['test'];
var obj = {
get latest () {
if (log.length == 0) return undefined;
return log[log.length - 1]
}
}
console.log (obj.latest); // Will return "test".