how to form an array of arrays in jQuery

Question

How to make an array of arrays like

{ [1,2,3],[2,3,4],[2,34,55] }

in jQuery ?

    $(document).ready(function() {
    var row = 4;
    var items = [];
    var total = [];
    $('#test tr:eq(' + row + ') td').each(function(colindex, col) {
        //alert(colindex);
        t = $(this).contents();
        items.length = 0;
        $.each(t, function(i, val) {
            if (val.tagName != 'BR') {
                if (val.innerHTML == undefined) {
                    items.push(val.data);
                }
                else
                    items.push(val.innerHTML);
            }
            //alert(items.toString());
        });
        total.push(items);
    });
    alert(total.toString());
});

iIn the above code I'm trying to create a array Total() with the elements as arrays (item()), but how ever the Total() array has only one object that too the last item() array.

{ [1,2,3],[2,3,4],[2,34,55] } => Object containing arrays. [[1,2,3],[2,3,4],[2,34,55]] => Array containing arrays — stecb
– stecb, Commented Apr 28, 2011 at 7:20
@stecb: { [1,2,3],[2,3,4],[2,34,55] } is an invalid object literal, not an object containing arrays (it doesn't have any property names). But yes, the correct notation for an array of arrays when written as a literal would indeed be [[1,2,3],[2,3,4],[2,34,55]]. — T.J. Crowder
– T.J. Crowder, Commented Apr 28, 2011 at 7:24

T.J. Crowder · Accepted Answer · 2011-04-28 07:20:17Z

3

The problem is that you're reusing the same items array on each loop. Instead, create a new items array:

$(document).ready(function() {
    var row = 4;
    var items;       // <============= Don't need to initialize here
    var total = [];
    $('#test tr:eq(' + row + ') td').each(function(colindex, col) {
        //alert(colindex);
        t = $(this).contents();
        items = [];  // <============== Create each new `items` array here
        $.each(t, function(i, val) {
            if (val.tagName != 'BR') {
                if (val.innerHTML == undefined) {
                    items.push(val.data);
                }
                else
                    items.push(val.innerHTML);
            }
            //alert(items.toString());
        });
        total.push(items);
    });
    alert(total.toString());
});

When you set the length property of an array to 0, you're removing all of its array elements but it's still the same array, so you ended up pushing the same array onto your totals array repeatedly.

answered Apr 28, 2011 at 7:20

T.J. Crowder

1.1m201 gold badges2k silver badges2k bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

T.J. Crowder Over a year ago

@deathcaller: Just to flag it up, see @guffa's note about your if (val.innerHTML == undefined) check. Really best to do if (typeof val.innerHTML === 'undefined') (note the === rather than just ==, although in this case, it doesn't matter all that much).

Guffa · Accepted Answer · 2011-04-28 07:27:43Z

Move the creation of the items array into the outer loop so that you create a new array for each iteration. Otherwise you will be adding the same array to total over and over, so you will end up with an array full of references to the same array, which contains only the values from the last iteration.

Don't use the undefined "constant", as it's not a constant. Check the type of the property instead.

$(document).ready(function() {
  var row = 4;
  var total = [];
  $('#test tr:eq(' + row + ') td').each(function(colindex, col) {
    t = $(this).contents();
    // create a new array for each iteration:
    var items = [];
    $.each(t, function(i, val) {
      if (val.tagName != 'BR') {
        if (typeof val.innerHTML == 'undefined') {
          items.push(val.data);
        } else {
          items.push(val.innerHTML);
        }
      }
    });
    total.push(items);
  });
  alert(total.toString());
});

Amadan · Accepted Answer · 2011-04-28 07:20:39Z

0

First of all, an array of arrays literal should have two sets of [], not mixed [] and {}: [ [1,2,3],[2,3,4],[2,34,55] ]

Also, instead of

items.length = 0;

do this:

var items = [];

What you're doing now is kind of like trying to expand your friend's circle of acquaintances by taking another person and introducing him to her repeatedly, only changing his clothes, wig and fake moustache every time. Despite the different looks, your friend will only get one new acquaintance.

answered Apr 28, 2011 at 7:20

Amadan

200k23 gold badges252 silver badges321 bronze badges

Collectives™ on Stack Overflow

how to form an array of arrays in jQuery

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related