Question

I got an array (see below for one object in the array) that I need to sort by firstname using JavaScript.
How can I do it?

var user = {
   bio: null,
   email:  "[e-mail]",
   firstname: "Anna",
   id: 318,
   lastAvatar: null,
   lastMessage: null,
   lastname: "Nickson",
   nickname: "anny"
};

Answer 1

Suppose you have an array users. You may use users.sort and pass a function that takes two arguments and compare them (comparator)

It should return

• something negative if first argument is less than second (should be placed before the second in resulting array)
• something positive if first argument is greater (should be placed after second one)
• 0 if those two elements are equal.

In our case if two elements are a and b we want to compare a.firstname and b.firstname

Example:

users.sort(function(a, b){
    if(a.firstname < b.firstname) { return -1; }
    if(a.firstname > b.firstname) { return 1; }
    return 0;
})

This code is going to work with any type.

Note that in "real life"™ you often want to ignore case, correctly sort diacritics, weird symbols like ß, etc. when you compare strings, so you may want to use localeCompare. See other answers for clarity.