Pseudo-element CSS dynamically using JavaScript

Question

Is it possible to set the CSS of a pseudo-element dynamically? For example:

jQuery dynamically styling help container

$('#help').css({
    "width" : windowWidth - xOffset,
    "height" : windowHeight - yOffset,
    "bottom" : -windowHeight,
    "left" : 200
});

jQuery Attempt at setting the inner border of the help container:

$('#help:before').css({
    "width" : windowWidth - xOffset,
    "height" : windowHeight - yOffset
});

CSS file for the above

#help
{
    opacity: 0.9;
    filter:alpha(opacity=90);   
    -moz-opacity: 0.9;          
    z-index: 1000000;
    bottom: -550px;
    left: 400px;
    background-color: #808080;
    border: 5px dashed #494949;
    -webkit-border-radius: 20px 20px 20px 20px;
    -moz-border-radius: 20px 20px 20px 20px;
    border-radius: 20px 20px 20px 20px;        
}
#help:before 
{
    border: 5px solid white;
    content: '';
    position: absolute;
    -webkit-border-radius: 20px 20px 20px 20px;
    -moz-border-radius: 20px 20px 20px 20px;
    border-radius: 20px 20px 20px 20px;          
}

possible duplicate of [Setting CSS pseudo-class rules from JavaScript](http://stackoverflow.com/questions/311052/setting-css-pseudo-class-rules-from-javascript) — thirtydot, Aug 23 '11 at 17:09

score 5 · Accepted Answer · edited May 23 '17 at 12:19

5

You can't do it directly through jQuery.

Look at this question: Setting CSS pseudo-class rules from JavaScript

@Box9's answer is probably the one you should actually use:

I threw together a small library for this since I do think there are valid use cases for manipulating stylesheets in JS.

edited May 23 '17 at 12:19

Community

1
1

answered Aug 23 '11 at 17:11

thirtydot

224,678
48
389
349

score 0 · Answer 2 · answered Aug 23 '11 at 17:02

0

Rather than setting the width and height using .css(), you should just use .width() and height() directly.

answered Aug 23 '11 at 17:02

Blazemonger

90,923
26
142
180

1

Can you post the code for this, my code doesn't work: $('#help:before').width(windowHeight - 410) .height(windowHeight - 210); – Jack Aug 23 '11 at 17:05

Pseudo-element CSS dynamically using JavaScript

2 Answers2

Linked