[JS] Push to multidimensional array, first element empty?

Fenster · 14-04-2014 02:08PM #1

On page load, I take a list of every image in each gallery element on the page, and push this to a temporary array. I then push this temporary array to a multidimensional array of all such gallery elements on the page.

However, the first element in the array comes up with a length of 0, and appears empty so far as I can tell. The arrays are getting pushed to indexes 1, 2, 3, etc., instead of 0, 1, 2.

var galleryImages = [[]];

$(window).load(function() {
    $('.' + galleryClass).each(function() { 
        var tmp = [];

        $(this).children('img').each(function() {
            tmp.push(this);
        });

        galImg.push(tmp);
    });
});

On this given page there are four galleries:

The first has 16 images.
The second has 15 images.
The third has 18 images.
The fourth has 34 images.

This is what I see when I output lengths:

$(galleryImages).each(function(index, element) {
    console.log('galleryImages[' + index + '].length: ' + element.length);
});

galleryImages[0].length: 0
galleryImages[1].length: 16
galleryImages[2].length: 15
galleryImages[3].length: 18
galleryImages[4].length: 34

What glaringly obvious thing have I missed here?

colm_c · 14-04-2014 04:52PM

Most likely because when you declare

var galleryImages = [[]];

You're actually setting galleryImages to be an array with one item in it, an empty array.

Just set it to empty (javascript doesn't care about multi dimensional arrays).

var galleryImages = [];

Fenster · 14-04-2014 05:21PM

Ah, brilliant, that was it. I declared as I did because I was told it was the Correct Way to declare a multidimensional array.

[JS] Push to multidimensional array, first element empty?

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