Better way to create arrays in javascript?

Question

I'm trying to create an array in Javascript with a size that is equivalent to the number of times a certain class is found in the DOM, and then iterate through it to grab the text from an input field present in that class. I can easily do this like so:

var count = 0;
$('.className').each(function() {
    count++;
});
var classes = new Array(count);
count = 0;
$('.className input[type=text]').each(function() {
    classes[count++] = $(this).val();
});

This looks like a lot of code for what seems to be a relatively simple task. Is there a more efficient or less lengthy way of doing this?

Thanks

There are obviously many possible improvements but I don't think this code does what you want it to do. — Denys Séguret
– Denys Séguret, Commented Jul 10, 2014 at 19:23
You don't need to initialize arrays, they're dynamic, just create an empty one, and start filling it up. — elclanrs
– elclanrs, Commented Jul 10, 2014 at 19:23
@dystroy it goes without saying that I am new to Javascript, however the code does currently work the way I want it to. — Michael Parker
– Michael Parker, Commented Jul 10, 2014 at 19:24
@MichaelParker: Then this sounds more like code review than stack overflow. — Matt Burland
– Matt Burland, Commented Jul 10, 2014 at 19:26
@MattBurland I didn't even know that existed. It does look like a better place to post this kind of question to. — Michael Parker
– Michael Parker, Commented Jul 10, 2014 at 19:28

Denys Séguret · Accepted Answer · 2014-07-10 19:24:41Z

6

It looks like you want this :

var classes = $('.className input[type=text]').map(function(){
    return this.value
}).get();

But it's a guess : it's not clear why you start by counting all elements of the class and then iterate on the inputs.

answered Jul 10, 2014 at 19:24

Denys Séguret

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1 Comment

Michael Parker Over a year ago

Yes, this is what I was looking for. The reason I counted the elements before creating my array was because I didn't know you could create arrays with an unspecified size. Still learning.

ColinE · Accepted Answer · 2014-07-10 19:25:20Z

3

You can construct an array of elements directly from your selector via the makeArray function, then transform the result using a map.

var classes = $.makeArray($('.className input[type=text]')).map(function() {
    return $(this).val();
});

answered Jul 10, 2014 at 19:25

ColinE

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Comments

Lucas Trzesniewski · Accepted Answer · 2014-07-10 19:25:22Z

2

Use jQuery's map function, then get if you need a pure array:

var values = $('.className input[type=text]').map(function() {
    return $(this).val();
}).get();

answered Jul 10, 2014 at 19:25

Lucas Trzesniewski

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Comments

Igor · Accepted Answer · 2014-07-10 19:25:13Z

1

each passes the index, so you don't need to do it yourself:

var classes = [];
$('.className input[type=text]').each(function(index, value) {
    classes[index] = $(this).val();
});

answered Jul 10, 2014 at 19:25

Igor

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Comments

War10ck · Accepted Answer · 2014-07-10 19:25:25Z

0

Arrays are dynamic and therefore don't need to be initialized. Create a new array, loop through the inputs and push the values to the new array:

var classes = [];
$('.className input[type=text]').each(function(idx, elem) {
    classes.push($(elem).val());
});

answered Jul 10, 2014 at 19:25

War10ck

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