What is the best method for applying classes to a collection of DOM elements with jQuery?

I attempted two different methods of iterating through the arrays, but encountered the same error:

addClass is not function

First attempt using a for loop:

function game(){
    var cards = $('.card');

    function initialize(){
        for(var x = 0; x < cards.length; x++) {    
            cards[x].addClass('wtf');    
        }
    };
};

Second try utilizing the each method:

function game(){
    var cards = $('.card');

    function initialize(){
        //Add random key values to pairs of cards
        $.each( cards ,function(i, ele) {    
            ele[i].addClass('wtf');
        });
    };
};

Is there a more effective way to handle these types of arrays?

Answer №1

Your code examples are not functioning correctly because you are trying to use a jQuery method, addClass, on a DOMElement rather than a jQuery object.

The addClass() method will handle the looping internally if multiple elements match the selector in the jQuery object, making it a one-line call:

function game(){
    var $cards = $('.card');

    function initialize() {
        $cards.addClass('wtf');
    };
};

How can I select and add a class to only the 5th card for example?

To achieve that, you can utilize the eq() method:

$cards.eq(4).addClass('wtf');

Remember that the index starts at zero, so the 5th element is actually index 4.

Answer №2

cards[x] represents a DOM element, and you can convert it into a jQuery object using $(cards[x]) as shown below.

function game() {
    var cards = $('.card');

    function initialize() {
        for (var x = 0; x < cards.length; x++) {
            //Update the following line.
            $(cards[x]).addClass('wtf');
        }
    };
};

You don't have to iterate through all elements. You can simply use cards.addClass('wtf') like this.

function game() {
    var cards = $('.card');

    function initialize() { 
        cards.addClass('wtf');
    };
};

If you need to select a specific card, you can utilize the eq() method as demonstrated below.

cards.eq(4).addClass('wtf');   //eq(4) will target the 5th card

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