json陣列去重函式

//json去重函式
//1、傳入json或陣列
//2、傳入去重的鍵名
function abs(arr,key_name){
    var new_arr = [];
    var i = 0;
    for(key in arr){
        var key_name_value = arr[key][key_name];
        var is_key_name_value = false;
        for(key1 in arr){
            if(key>key1 && key_name_value==arr[key1][key_name]){
                is_key_name_value 
 
= true;
                break;
            }
        }
        if(is_key_name_value===false){
            new_arr[i] = arr[key];
            i++;
        }
    }
    return new_arr;
}

//定義json
var a = [{user_id: "WV00000002", user_name: "王維", work_date: "2020-08-06", class_id: 9, classes_name: "顏色測試"},
{user_id: 
 
"WV00000002", user_name: "王維", work_date: "2020-08-14", class_id: 1, classes_name: "早班"}
,{user_id: "WV00000004", user_name: "張穎", work_date: "2020-08-09", class_id: 9, classes_name: "顏色測試"},{user_id: "WV00000005", user_name: "王發通", work_date: "2020-08-15", class_id: 9, classes_name: "顏色測試"},{user_id: "WV00000007", user_name: "宋葉飛", work_date: "2020-08-06", class_id: 9, classes_name: "顏色測試"}];

 
//呼叫json去重
var result = abs(a,'class_id');

//列印json
console.log(result);