How can I find the index of an object inside a Array using underscore.js?

Question

I want to get the index of the given value inside a Array using underscore.js.

Here is my case

var array = [{'id': 1, 'name': 'xxx'},
             {'id': 2, 'name': 'yyy'},
             {'id': 3, 'name': 'zzz'}];

var searchValue = {'id': 1, 'name': 'xxx'};

I used the following code,

var index = _.indexOf(array, function(data) { 
                alert(data.toSource()); //For testing purpose 
                return data === searchValue; 
            });

Also tried this too

var index = _.indexOf(array, {id: searchValue.id});

But it returns -1 . Since it does not enter into that function. So I didn't get that alert message.

Whats wrong with my code. Can anyone help me?

Answer 1

I'd strongly suggest taking a look at lodash. It contains quite a bit of nifty little functions that unfortunately underscore is lacking.

For example, this is what you would do with lodash:

var array = [{'id': 1, 'name': 'xxx'},
           {'id': 2, 'name': 'yyy'},
           {'id': 3, 'name': 'zzz'}];

var searchValue = {'id': 1, 'name': 'xxx'};


var index = _.findIndex(array, searchValue); 
console.log(index === 0); //-> true

http://lodash.com/docs#findIndex

Also, if you're bound to using Underscore - you can grab lodash's underscore build at https://raw.github.com/lodash/lodash/2.4.1/dist/lodash.underscore.js

---

ES2015

With ES2015 now in wide use (through transpilers like Babel), you could forego lodash and underscore for the task at hand and use native methods:

var arr = [{ id: 1 }, { id: 2}];

arr.findIndex(i => i.id === 1); // 0