关于reduce的使用方法

    var rowData=[
        {data:4,date:‘06‘,code:‘cr_3‘,name:‘桥吊3‘},
        {data:1,date:‘03‘,code:‘cr_1‘,name:‘桥吊1‘},
        {data:2,date:‘01‘,code:‘cr_2‘,name:‘桥吊2‘},
        {data:1,date:‘07‘,code:‘cr_1‘,name:‘桥吊1‘},
        {data:2,date:‘02‘,code:‘cr_2‘,name:‘桥吊2‘},
        {data:1,date:‘09‘,code:‘cr_1‘,name:‘桥吊1‘},
        {data:2,date:‘03‘,code:‘cr_2‘,name:‘桥吊2‘}
    ];
    var arr=rowData.reduce(function(o,v,i){
        if(o[v.code]){
            o[v.code].push(v.data);
        }else{
            o[v.code]=[v.data];
        }
        return o;
    },{})
    console.log(arr);

    {
        "cr_1":[1,1,1],
        "cr_2":[2,2,2],
        "cr_4":[4]
    }