How to assign a Javascript array through it's indexes

Question

Possible Duplicate:
Dynamically creating keys in javascript associative array

usually we initialize an array like this:

var ar = ['Hello', 'World'];

And for access to it's values we do:

alert(ar[0]); // Hello

But I want a custom index to assign, ex:

var ar = ['first' => 'Hello', 'second' => 'World'];

and then

alert(ar['first']);

But I can't find how, is there something like this that I could do for assign?

Thank's!

There is no such thing as associative arrays in JavaScript. You either have arrays with numeric indices, or you have objects: unordered collections of keys and values — Bergi, Dec 05 '12 at 20:36

score 2 · Accepted Answer · answered Dec 05 '12 at 20:35

2

You could use Object instead of Array, you can specify named properties for object

var ar = {
  first: 'hello',
  second: 'world'
};
alert(ar['first']);

Also you can just assign properties with string keys to your array, this will also work:

var ar = [];
ar['first'] = 'first';
alert(ar['first']);

answered Dec 05 '12 at 20:35

Ivan Solntsev

2,081
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Actually I didn't know I could access to an object's node as a string key, but now I know, Thank's to everyone! – Neo Dec 05 '12 at 20:43

score 2 · Answer 2 · answered Dec 05 '12 at 20:35

2

You need to use an Object.

var obj = {'first': 'hello', 'second': 'world'};

alert(obj.first);

answered Dec 05 '12 at 20:35

barro32

2,559
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RonaldBarzell · Answer 3 · 2012-12-05T20:47:47.137

1

You can do this:

var ar = {
   'first' :'Hello', 
   'second' : 'World'
 };

As you can see, this is the way you initialize objects in Javascript. Javascript blurs the lines between associative arrays and objects.

You can then access this with:

ar['first']

Or even:

ar.first

Also, you could leave out the quotes in the key initialization, like so:

var ar = {
   first :'Hello', 
   second : 'World'
 };

edited Dec 05 '12 at 20:47

answered Dec 05 '12 at 20:35

RonaldBarzell

3,822
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Note that this isn't an array anymore. (But it never was -- proper arrays don't have named indexes.) – Dec 05 '12 at 20:35
Please explain the differences between his array form `['value']` and your object-form `{'key' : 'value'}`. – David Thomas Dec 05 '12 at 20:35
@DavidThomas: This is just the way you initialize hashes/objects in javascript. Javascript blurs the lines between the two. You can do ar['first'] at this point or even ar.first. – RonaldBarzell Dec 05 '12 at 20:37
Thank's! Yeah I know this is an object, but it works for me as well, I just want to get the indexes through a class parameter for send it's value to a php file, again Thank you very much :) – Neo Dec 05 '12 at 20:40
@user1161318, yeah, I know. I was asking you to explain for the OP's benefit... =) – David Thomas Dec 05 '12 at 20:45
@DavidThomas: Oops! I will go ahead and edit the answer. Good call. – RonaldBarzell Dec 05 '12 at 20:46

score 1 · Answer 4 · answered Dec 05 '12 at 20:36

Objects in JavaScript are just property bags (hashtables).

You can:

var ar = {};
ar["name"] = "Dave";
ar["salary"] = "Millions";

alert(ar.name);  //Dave
alert(ar["salary"]);  //millions

JavaScript allows you to be pretty flexible in how you create these objects.

score 1 · Answer 5 · answered Dec 05 '12 at 20:36

JavaScript doesn't have associative arrays as such, but object literals:

var obj = {foo:'bar'};
obj.something = 'else';
//or:
obj['foo'] = 'BAR';

JS won't make a fuss if you create named indexes on an array (because the Array object traces back to the Object prototype) but you'll loose all use of Array features (methods like sort, or the magic length property, to name just a few)

score 1 · Answer 6 · answered Dec 05 '12 at 20:36

just use

    var h = new Object(); // or just {}
h['one'] = 1;
h['two'] = 2;
h['three'] = 3;

// show the values stored
for (var k in h) {
    // use hasOwnProperty to filter out keys from the Object.prototype
    if (h.hasOwnProperty(k)) {
        alert('key is: ' + k + ', value is: ' + h[k]);
    }
}

How to assign a Javascript array through it's indexes

6 Answers6