json數組根據其中一個屬性進行分類重組

let arr=[
      {
        "color": "red",
        "iconName": "class1",
        "name": "菜單一",
        "styleName": "分類名稱1",
        "url": "index1"
      },
      {
        "color": "red",
        "iconName": "calss2",
        "name": "菜單二",
        "styleName": "分類名稱2",
        "url": "index2"
      },
      {
        "color": "blue",
        "iconName": "calss3",
        "name": "菜單三",
        "styleName": "分類名稱3",
        "url": "index3"
      }
    ];
var map = {},dest = [];
for(var i = 0; i < arr.length; i++){
    var ai = arr[i];
    if(!map[ai.styleName]){
        dest.push({
            styleName: ai.styleName,
            data: [ai]
        });
        map[ai.styleName] = ai;
    }else{
        for(var j = 0; j < dest.length; j++){
            var dj = dest[j];
            if(dj.styleName == ai.styleName){
                dj.data.push(ai);
                break;
            }
        }
    }
}
console.log("dest:"+JSON.stringify(dest));