jQuery: How to check if an element exists and change css property

Question

First of all, sorry if this is a simple question. I am new to jQuery and I want to know how can I check if an element exists and if it does, change the css property.

Here is what I mean: I have the following list:

<ul class="element-rendered">
    <li class="element-choice">Item A</li>
    <li class="select-inline">Item B</li>
</ul>

I want to know how can I check if the class select-inline exists inside element-rendered and if it does, how can I change the css background of element-choice to blue?

I created a fiddle to reproduce this example.

Again sorry if this is a simple question but I am new to jQuery.

Answer 1

You can use .length to check if the element exists in DOM.

$('.element-rendered .select-inline') will select all the elements having class select-inline inside the element with class element-rendered. .length on selector will return the number of matched elements. So, number greater that one, means the element exists. Then you can use .css to set inline styles.

Demo

if ($('.element-rendered .select-inline').length) {
  $('.element-choice').css('background', 'blue');
}

.element-choice {
  width: 100%;
  background: red;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.10.1/jquery.min.js"></script>
<ul class="element-rendered">
  <li class="element-choice">Item A</li>
  <li class="select-inline">Item B</li>
</ul>

---

I'll also recommend you to use class in CSS and add it to the element by using addClass.

Demo