Adding new element to associative array each click

Question

This is probably very easy, but I just can't figure out how to solve it right now. Each time a submit button is clicked, the function below checks input field 1 (name), and if not empty adds the value to an associative array, and continue with the description.

What I want is to add a new level 1 element to the array every click, that should hold these value, so that it after three clicks looks like this:

Click 1:
    listObject[0]['listObjectName'] = 'Name 1';
    listObject[0]['listObjectDesc'] = 'Desc 1';

Click 2:
    listObject[1]['listObjectName'] = 'Name 2';
    listObject[1]['listObjectDesc'] = 'Desc 2';

Click 3:
    listObject[2]['listObjectName'] = 'Name 3';
    listObject[2]['listObjectDesc'] = 'Desc 3';

The function:

$('#addListObjectSubmit').click(function (e) {

            var listObjectName = $('#m_newListObject').val();

            if((listObjectName == null) || (listObjectName == '')) {
                return false;
            }
            else {
                listObjects['listObjectName'] = listObjectName;

                var listObjectDesc = $('#m_newListObjectDesc').val();

                if ((listObjectDesc == null) || (listObjectDesc == '')) {
                    listObjects['listObjectDesc'] = null;
                }
                else {
                    listObjects['listObjectDesc'] = listObjectDesc;
                }
            }

            e.preventdefault();
        });

So, what is the best way of dealing with this?

kapa · Accepted Answer · 2012-10-25 22:25:24Z

5

It will help you a bit if you forget about associative arrays. They only theoretically exist in Javascript. In fact, everything is an object, even arrays. But thinking in data storage terms, you can use a simple array that can only be indexed numerically, or you can use an object as a data map.

The following example creates an array (note the more compact [] instead of new Array()) and pushes a map (created with {}) into it:

var listObjects = [];
...
var newElem = {
    'listObjectName' : 'Name 1',
    'listObjectDesc' : 'Desc 1'
};
listObjects.push(newElem);

Afterwards, you can access this element with listObjects[0], if it was the first element in the array.

If you want to access its properties, you can use one of these:

listObjects[0].listObjectName
listObjects[0]['listObjectName']

So you can see that when dealing with objects, you can use the . notation as well as the bracket notation - they are equivalent, but the latter form makes it look like it is an "associative array" (even more for people coming from PHP).

edited Oct 25, 2012 at 22:25

answered Oct 25, 2012 at 22:14

kapa

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2 Comments

holyredbeard Over a year ago

I've been into php too much lately, almost forgot the object nature of js. Thank you for refreshening my memory :)

kapa Over a year ago

@holyredbeard Just extended my answer a bit more. I was sure you came from a PHP background actually ;).

redShadow · Accepted Answer · 2012-10-25 22:16:02Z

2

..you mean, you want to add an "associative array" (they're called "objects", in JavaScript, btw) to an array on each click?

The method to add things to arrays is push():

listObject.push({
    'listObjectName': 'Name X',
    'listObjectDesc': 'Description X'
})

answered Oct 25, 2012 at 22:16

redShadow

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