Question

3

1

Say I have an array of JS objects:

var objs = [ { first_nom: 'Lazslo',last_nom: 'Jamf' },
            { first_nom: 'Pig', last_nom: 'Bodine'  },
            { first_nom: 'Pirate', last_nom: 'Prentice' }
           ];

How can I sort them by the value of last_nom in JavaScript. I know about sort(a,b) but that only seems to work on strings and numbers. Do I need to add a toString method to my objects?

Thanks in advance.

flag	asked Jul 15 at 3:17 Tyrone Slothrop 41●4

Wogan · Accepted Answer · 2009-07-15 03:35:51Z UTC

6

It's easy enough to write your own comparison function:

function compare(a,b) {
  if (a.last_nom < b.last_nom)
     return -1;
  if (a.last_nom > b.last_nom)
    return 1;
  return 0;
}

objs.sort(compare);

answered Jul 15 at 3:35

Wogan
119●3

thanks. Didn't know that sort took a function ref. – Tyrone Slothrop Jul 15 at 3:45

Baversjo · Answer 2 · 2009-07-15 03:38:04Z UTC

2

This script allows you to do just that unless you want to write your own comparison function or sorter:

http://www.thomasfrank.se/sorting_things.html

edited Jul 15 at 3:38

answered Jul 15 at 3:31

Baversjo
172●10

kennebec · Answer 3 · 2009-07-15 04:03:38Z UTC

If you have duplicate last names you might sort those by first name-

obj.sort(function(a,b){
  if(a.last_nom< b.last_nom) return -1;
  if(a.last_nom >b.last_nom) return 1;
  if(a.first_nom< b.first_nom) return -1;
  if(a.first_nom >b.first_nom) return 1;
  return 0;
}

Christoph · Answer 4 · 2009-07-15 07:21:48Z UTC

Instead of using a custom comparison function, you could also create an object type with custom toString() method (which is invoked by the default comparison function):

function Person(firstName, lastName) {
    this.firtName = firstName;
    this.lastName = lastName;
}

Person.prototype.toString = function() {
    return this.lastName + ', ' + this.firstName;
}

var persons = [ new Person('Lazslo', 'Jamf'), ...]
persons.sort();

Sorting objects in an array by a field value in JavaScript

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