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.

if($('.element-rendered .select-inline').length) { $('.element-choice').css('background', 'blue'); } Check updated fiddle — Tushar
– Tushar, Commented Oct 7, 2015 at 14:44
Hey @Tushar thank you again! You are always helping me here! haha! That worked. Would you mind answer that so I can mark as correct? — brunodd
– brunodd, Commented Oct 7, 2015 at 14:47
$('.element-rendered .select-inline').css("background-color", "red") will (almost) be a no-op if the element is not found in the DOM. You could go without checking the existance at all — Andreas
– Andreas, Commented Oct 7, 2015 at 14:48

Tushar · Accepted Answer · 2015-10-07 14:56:46Z

3

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

edited Oct 7, 2015 at 14:56

answered Oct 7, 2015 at 14:49

Tushar

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Comments

Noldor · Accepted Answer · 2015-10-07 14:48:51Z

1

var eR = $(".element-rendered");
if (eR.find(".select-inline").length > 0){
  eR.find(".element-choice").css("color", "blue");
}

answered Oct 7, 2015 at 14:48

Noldor

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Comments

Sean Wessell · Accepted Answer · 2015-10-07 14:49:39Z

1

This would work for your specific example.

Find the select-line element which is a child of element-rendered. The find all of the sibling elements with class element-choice and apply the css.

$('.element-rendered>.select-inline').siblings('.element-choice').css('background','blue')

http://jsfiddle.net/SeanWessell/hjpng78s/3/

answered Oct 7, 2015 at 14:49

Sean Wessell

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Comments

guest271314 · Accepted Answer · 2015-10-07 15:31:04Z

1

To check if element exists could use .is() , or as suggested by @Tushar .length

var container = $(".element-rendered");
// alternatively `!!$(".select-inline", container).length`
$(".select-inline", container).is("*") 
&& $(".element-choice", container).css("background", "blue");

jsfiddle http://jsfiddle.net/hjpng78s/6/

edited Oct 7, 2015 at 15:31

answered Oct 7, 2015 at 14:56

guest271314

1

3 Comments

Tushar Over a year ago

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

Tushar Over a year ago

I'll suggest you to use length instead of is, I think .length will be slightly faster than is

guest271314 Over a year ago

@Tushar Added suggestion to use .length for performance instead of .is() to post

Diptox · Accepted Answer · 2015-10-07 14:59:54Z

0

Demo

if($(".element-rendered .select-inline")[0])
    $(".element-rendered .select-inline").css("background-color","red");

edited Oct 7, 2015 at 14:59

answered Oct 7, 2015 at 14:48

Diptox

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3 Comments

Andreas Over a year ago

It doesn't work correctly. The selector in my link doesn't match an element but it still changes the background color.

Tushar Over a year ago

@Diptox jQuery selector returns an Object, and objects are always truthy, even if the object is empty

Diptox Over a year ago

my fault , forget the [0] front of the selector

lshettyl · Accepted Answer · 2015-10-07 15:00:46Z

0

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?

if ( $(".element-rendered > .select-inline").length ) {
    $(".element-rendered > .element-choice").css({
        'background-color': 'blue'
    });
}

Docs:

edited Oct 7, 2015 at 15:00

answered Oct 7, 2015 at 14:46

lshettyl

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