json数据按照某一个相同键值进行分类成一个新的二维json数组

 var map = {},
        jobarr = [];
    for (var i = 0; i < jobs.length; i++) {
        var ai = jobs[i];
        if (!map[ai.dep]) {
            jobarr.push({
                dep: ai.dep,
                item: [ai]
            });
            map[ai.dep] = ai;
        } else {
            for (var j = 0; j < jobarr.length; j++) {
                var dj = jobarr[j];
                if (dj.dep == ai.dep) {
                    dj.item.push(ai);
                    break;
                }
            }
        }
    }