Sort the Keys of an Object with JavaScript

JavaScript objects store key‑value pairs, but their keys do not follow an arbitrary order. For ordinary string keys, rebuilding an object in a chosen order can make output easier to read. Array‑index keys have their own ordering rule, though, so this is not a general‑purpose way to store a sorted sequence.

This can be achieved fairly easily by:

1. Getting an array of the object's keys;
2. Sorting them;
3. Using reduce() to rebuild the object, in the order of the keys.

For example:

const sortObject = obj => {
  // get the keys of the object
  var keys = Object.keys(obj);

  // sort the keys
  keys.sort();

  // use reduce to rebuild the object
  return keys.reduce((sortedObj, key) => {
    sortedObj[key] = obj[key];
    return sortedObj;
  }, {});
};

You could use this function like this:

let myObj = { c: 1, a: 2, b: 3 };

console.log(sortObject(myObj));
//=> {a: 2, b: 3, c: 1}

Do bear in mind that this method will create a new object, rather than modifying the original one.

Also, If you want to sort the object numerically, you would need to pass a function as a parameter to the sort method like this:

keys.sort((a, b) => {
  return a - b;
});

Easy!