Dynamically creating elements using jQuery

Question

I am building a list of checkbox items in jQuery based on an array returned from a handler.

The containing element is the .listContainer element below and then each dynamic element I want to add to this takes the form of the .listContainerItem element. Each item will have checkbox value and label based on the array item creating it.

<div class="listContainer">
    <div class="listContainerItem">
        <input type="checkbox" value="1" />
        <div class="listContainerItemLabel">Checkbox 1</div>
    </div>
</div>

At the point of the function that has the array passed to it, what is the most efficient way of creating this? I have been trying to accomplish it as below, but quickly running into major performance issues.

function AddItemToListContainer(item) {
    var currentItems = $j("#listContainerAvailable .listContainerItem");
    if ($j.grep(currentItems, function (e) { return $j(e).find(":checkbox:first").val() == item.Id; }).length === 0) {
        labelDiv = $j("<div />").addClass("listContainerItemLabel").html(item.Text);
        itemToAdd = $j("<div />").addClass("listContainerItem").append("<input type=\"checkbox\" value=\"" + item.Id + "\" />").append(labelDiv);
        currentItems.append(itemToAdd);
    }
}

I've looked at .map function, but not sure quite how to implement it. Can someone point me in the right direction?

Answer 1

I would start with something like this:

var $container = $j('#listContainerAvailable');
var checkboxes = {};

function AddItemToListContainer(item) {
    if (checkboxes[item.Id]) return false;

    checkboxes[item.Id] = true;

    var $item = $j('<div />', {
        'class': 'listContainerItem',
    }).appendTo($container);

    $j('<input />', {
        'type': 'checkbox',
        'value': item.Id
    }).appendTo($item);

    $j('<div />',  {
        'class': 'listContainerItemLabel',
        'text': item.Text
    }).appendTo($item);
}

As long as none of these elements exist when you create the page, you can add them to a hash table instead of searching through the DOM. I think you'd also benefit from a JS templating engine like mustache.js

Answer 2

Are you wanting to have these elements appear one at a time? or just be dynamically created from an array on page load?

For the last:

html

    <div class="listContainer">
       <div class="listContainerItem"></div>
     </div>  

and jquery

var array = ['1', '2', '3', '4', '5'];

 $.each(array, function (index, value) {
    $(".listContainerItem").append('<input type="checkbox" value="' + value + '" /> <div         class="listContainerItemLabel">Checkbox ' + value + '</div>');
 });

http://jsfiddle.net/jeremythuff/HEKjk/

And some .click events can give you the first effect