Is it necessary to check if element has attribute?

Question

I'm using data attributes in HTML elements

Example:

<div class="fruit" data-color="red">...</div>

In jQuery I'm getting the data attribute using $(this).data("color") and adding it has a class name to the element.

Is it necessary to validate first if a data attribute exists before adding it as a class? Example:

// $(this) is .fruit div
if ( $(this).data("color") ) {
   $(this).addClass($(this).data("color")); //adds data value as class to element
}

or does jQuery handle that? I tried running the code without the if statement and I don't get any errors if the element has no "color" data attribute. I'm guessing that jQuery just ignores it.

Answer 1

jQuery handles that for you - in fact it's very robust in what it will accept for most method parameters without throwing any errors.

In this case if the data attribute is not found (or has no value) it will return undefined. If you then addClass(undefined) jQuery will perform no action on the selected elements.