can you help me understand why this is not working?

var elementTab1 = $('#tab1 .item-media.modificato');
elementTab1[0].addClass('selezionato');

this through this error

TypeError: undefined is not a function (evaluating 'elementTab1[0].addClass('selezionato')')

Thanks

can you help me understand why this is not working?

var elementTab1 = $('#tab1 .item-media.modificato');
elementTab1[0].addClass('selezionato');

this through this error

TypeError: undefined is not a function (evaluating 'elementTab1[0].addClass('selezionato')')

Thanks

• javascript
• jquery
• arrays
• addclass

• You probably don't want that . before the class name. – Pointy Commented Dec 23, 2014 at 22:08
• Yes, just a typo error writing the question, edited, thanks:) – elledienne Commented Dec 23, 2014 at 22:08

2 Answers 2

elementTab1 is already a jQuery object. It contains an array of matched elements in the DOM. Accessing the first index using [0] will return a native element with access to the native JavaScript API (and not jQuery's).

jQuery does provide a nice way to grab items from the array though. It is .eq().

elementTab1.eq(0).addClass('selezionato');

Accessing an element of a JQuery object (via your elementTab1[0]) call returns the DOM element, not a JQuery element.

DOM elements do not have an .addClass method.

The following code should work for you:

$(elementTab1[0]).addClass(".selezionato");

Alternately, just skip JQuery and use the native DOM APIs:

document
   .querySelector("#tab1 .item-media.modificato")
   .classList
   .add(".selezionato");