Javascript :: Sort array of objects / Custom sorting

A common issue is handling array sorting when unable to test/validate the code as is common with low-code tooling.

To that end, sorting can usually be done by setting a comparison function.

The comparison function takes two values as input and must return a value with the following rules:

input: two values, for the examples below these will be named itemA and itemB

output: a numeric value that when it's 0 no changes for the positions of itemA and itemB in relation to each other, if positive (>0) then itemA will be placed before itemB and if negative, itemB will be placed before itemA.

The items in the parameters can be objects or values, it's a matter of using the relevant fields/members for the object to deliver a return value.

Comparer function examples:

• for values:

function compareItems(itemA, itemB) {
  if (itemA > itemB) return 1;
  if (itemA < itemB) return -1;
  return 0; // if it's not one of the above, they're the same
}

• for objects:

function compareItems(itemA, itemB) {
  if (itemA.numberVal > itemB.numberVal) return 1;
  if (itemA.numberVal < itemB.numberVal) return -1;
  return 0; // if it's not one of the above, they're the same
}

Fully working examples below:

• Using a compare function:

function compareItems(itemA, itemB) {
  if (itemA > itemB) return 1;
  if (itemA < itemB) return -1;
  return 0; // if it's not one of the above, they're the same
}

var myArray = [3, 2, 4, 1];
myArray.sort(compareItems);
console.log(JSON.stringify(myArray));
//outputs: [1,2,3,4]

• Using an inline comparison function:

var myArray = [3, 2, 4, 1];
myArray.sort(function compareItems(itemA, itemB) {
  if (itemA > itemB) return 1;
  if (itemA < itemB) return -1;
  return 0; // if it's not one of the above, they're the same
});
console.log(JSON.stringify(myArray));
//outputs: [1,2,3,4]

• Using an inline comparison arrow function:

var myArray = [3, 2, 4, 1];
myArray.sort((itemA, itemB) => {
  if (itemA > itemB) return 1;
  if (itemA < itemB) return -1;
  return 0; // if it's not one of the above, they're the same
});
console.log(JSON.stringify(myArray));
//outputs: [1,2,3,4]