Javascript putting values in two-dimensional array

Question

Is there a better way to create a two-dimensional array in javascript than this?

var divcookies = new Array();
divcookies[0] = new Array(2);
divcookies[0][0] = name;
divcookies[0][1] = value;

This results in a two dimensional array with bad data added in the middle of it. I expect an array like this.

(name1, value1, name2, value2, name3, value3)

Instead I get this.

(name1, value2, ,name2, value2, name3, value3)

I don't really know when that extra bad data is added because if I alert during the loop that fills the array it only seems to loop through 3 times to put the three pairs of values expected.

So I am looking for a different way to get the two dimensional array.

function get_cookies_array() {

    var divcookies = new Array();

    if (document.cookie && document.cookie != '') {
        var split = document.cookie.split(';');
        for (var i = 0; i < split.length; i++) {
            var name_value = split[i].split("=");
            name_value[0] = name_value[0].replace(/^ /, '');
            if ( name_value[0].search("compage") != -1 ) {
               alert (divname+" "+ divarray);
               divcookies[i] = new Array(2);
               divcookies[i][0] = decodeURIComponent(name_value[0]);
               divcookies[i][1] = decodeURIComponent(name_value[1]);
            }
        }
    }

    alert (divcookies);

    return divcookies;

}

jsBin http://jsbin.com/iwuqab

No it is not the best way. However what are you trying to do? Here is a cookie script quirksmode.org/js/cookies.html — mplungjan
– mplungjan, Commented Aug 5, 2011 at 19:32

Marc B · Accepted Answer · 2011-08-05 19:30:05Z

3

The recommended method for creating arrays in JS is to NOT use the 'new' method. Instead, do:

var divcookies = [];
divcookies[0] = [];
divcookies[0][0] = name;
divcookies[0][1] = value;

This notation frees you up from having to specify element numbers in advance. Once a variable's been initialized as an array, you can set any index you want. The downside (regardless of which notation you use) is that you have to initialize every sub-array as well.

answered Aug 5, 2011 at 19:30

Marc B

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1 Comment

user823527 Over a year ago

this did not fix the problem of having the extra data in the array.

Jiri Kriz · Accepted Answer · 2011-08-05 21:46:01Z

1

Your 2-dimensional array is set up correctly (well, [] is preferred instead of new Array()). The actual problem is only with the display of your array using alert(divcookies). Here, divcookies is converted to a string using the predefined method toString(). This method creates a list of comma-separated array elements, from the first element to the last element. If some elements in between are not set, an empty string is output. In your case, you are not assigning to those indexes i of divcookies for which name_value[0].search("compage") == -1. These are the gaps ,, in the alerted list.

answered Aug 5, 2011 at 21:46

Jiri Kriz

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1 Comment

user823527 Over a year ago

Thanks so much. You found the problem.

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