Convert array of objects to an object in javascript

Question

I have an array of objects with below value

var arr = 
[{"Id":"0QL8W000006RHl1WAG","Sortorder":"1"}, 
          {"Id":"0QL8W000006RHl0WAG","Sortorder":"2"}, 
           {"Id":"0QL8W000006RHl2WAG","Sortorder":"3"}
          ]

Now I want to convert it to an object with below format.

var arr = {0QL8W000006RHl1WAG=1,0QL8W000006RHl0WAG=2,0QL8W000006RHl2WAG=3}

I have really tried most of the javascript methods for this with no success.

Please help on this. It's really very very urgent.

Answer 1

For the desired output , you essentially need a JS Map data structure.

Why are we using a Map over a JS object : https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#objects_vs._maps

Step 1 : Convert each object in the array to an array itself using the map method :

const arrayObj = [{"Id":"0QL8W000006RHl1WAG","Sortorder":"1"}, {"Id":"0QL8W000006RHl0WAG","Sortorder":"2"}, {"Id":"0QL8W000006RHl2WAG","Sortorder":"3"} ];

const mappedArrayObj = arrayObj.map(obj => [obj.Id, obj.Sortorder]);

Our 1st step produced an array of array(mappedArrayObj) as below:

[
  [ '0QL8W000006RHl1WAG', '1' ],
  [ '0QL8W000006RHl0WAG', '2' ],
  [ '0QL8W000006RHl2WAG', '3' ]
]

Step 2 : Convert the mappedArrayObj to a JS map using Map constructor as below :

const mapOfObjects = new Map(mappedArrayObj); 

This will produce output (console.log(mapOfObjects);) as below :

{
  '0QL8W000006RHl1WAG' => '1',
  '0QL8W000006RHl0WAG' => '2',
  '0QL8W000006RHl2WAG' => '3'
}

Answer 2

An alternative to @Rohit's approach is to use Array.reduce functionality:

const arrayObj = [{"Id":"0QL8W000006RHl1WAG","Sortorder":"1"}, {"Id":"0QL8W000006RHl0WAG","Sortorder":"2"}, {"Id":"0QL8W000006RHl2WAG","Sortorder":"3"} ];

const result = arrayObj.reduce(
    (target, item) => (target[item.Id] = item.Sortorder, target),
    {});

The {} is the initial empty object to return (what becomes the target in the reducer), while the "reducer function" simply:

1. Sets the property on that object with the name taken from the item's Id and sets it to the item's Sortorder (target[item.Id] = item.Sortorder) then
2. Uses the comma operator to ensure that the function returns the target object for the reducer chaining (, target).

By "chaining" the target object in this way, this avoids creating garbage that must be collected - we simply add properties to that one JavaScript object.