合并两个javascript对象，添加通用属性值

无法对对象的属性进行排序，但是可以对数组进行排序：

var merged = $.extend({}, a);for (var prop in b) {    if (merged[prop]) merged[prop] += b[prop];    else merged[prop] = b[prop];}// Returning merged at this point will give you a merged object with properties summed, but not ordered.var properties = [];for (var prop in merged) {    properties.push({        name: prop,        value: merged[prop]    });}return properties.sort(function(nvp1, nvp2) {    return nvp1.value - nvp2.value;});