Append serial number property to array of objects in javascript

Question

I have an array of objects in javascript.

var obj_arr = 
[{
    DATA_ID: 281,
    DATA_NAME: 'CIM',
    DATA_STATE: '0'
},
{
    DATA_ID: 382,
    DATA_NAME: 'CIMx',
    DATA_STATE: '0' 
},
{
    DATA_ID: 482,
    DATA_NAME: 'CIMy',
    DATA_STATE: '1' 
}]

I would like to append a serial number to each of the object in this array. The appended object will look something like this;

var obj_arr_appended = 
[{
    SERIAL_NO: 1,
    DATA_ID: 281,
    DATA_NAME: 'CIM',
    DATA_STATE: '0'
},
{
    SERIAL_NO: 2,
    DATA_ID: 382,
    DATA_NAME: 'CIMx',
    DATA_STATE: '0' 
},
{
    SERIAL_NO: 3,
    DATA_ID: 482,
    DATA_NAME: 'CIMy',
    DATA_STATE: '1' 
}]

The serial number will auto-increment. I am using node.js v6

Answer 1

With array.map you can run a function on each element:

var obj_arr_appended = obj_arr.map(function(currentValue, Index) {
   currentValue.SERIAL_NO = Index
   return currentValue
})

Answer 2

This code should work.

var obj_arr = 
    [{
        DATA_ID: 281,
        DATA_NAME: 'CIM',
        DATA_STATE: '0'
    },
    {
        DATA_ID: 382,
        DATA_NAME: 'CIMx',
        DATA_STATE: '0' 
    },
    {
        DATA_ID: 482,
        DATA_NAME: 'CIMy',
        DATA_STATE: '1' 
    }]    

    for (let i = 0; i < obj_arr.length; i++) {
            obj_arr[i]["SERIAL_NO"] = i;
        }

    console.log(obj_arr);