js隨機分組

var listall=[
        {name:'1'},{name:'2'},{name:'3'},{name:'4'},{name:'5'},{name:'6'},{name:'7'},
        {name:'8'},{name:'9'},{name:'10'},{name:'11'},{name:'12'},{name:'13'},{name:'14'},
        {name:'15'},{name:'16'},{name:'17'},{name:'18'},{name:'19'},{name:'20'}
        ];
    /*
    *
    * 解決數組中對象隨機分組問題
    * list:要分組的數組
    * num:分成的組數
    * */
    function changelist(list,num) {
        var n=list.length-1;//獲取數組下標的上限
        var length=n/num;//獲取分組後單組的長度
        var list1=list,list2=[];
        for(var i=0;i<num;i++){//根據分組數，確定遍歷次數
            var newlist=[];
            for(var j=0;j<length;j++){
                var id=Math.ceil(Math.random(0,list1.length-1)*list1.length-1);//獲取下標範圍內的隨機數
                newlist.push(list1[id]);//將獲取的對象放入定義的變量數組中
                list1.splice(id,1);//從數組中清除當前項
            }
            list2.push(newlist);//將變量數組放入結果組數中
        }
        return list2;
    }
    var morelist=changelist(listall,2);
    console.log(morelist);