JavaScript Set CSS :After Styles

Changing pseudo-element style from javascript

Since pseudo-elements do not exist in the DOM, they cannot be accessed in Javascript.
The workaround is to create a <span> instead of using :before and the same logic has to be applied.

Selecting and manipulating CSS pseudo-elements such as ::before and ::after using javascript (or jQuery)

You could also pass the content to the pseudo element with a data attribute and then use jQuery to manipulate that:

In HTML:

<span>foo</span>

In jQuery:

$('span').hover(function(){
    $(this).attr('data-content','bar');
});

In CSS:

span:after {
    content: attr(data-content) ' any other text you may want';
}

If you want to prevent the 'other text' from showing up, you could combine this with seucolega's solution like this:

In HTML:

<span>foo</span>

In jQuery:

$('span').hover(function(){
    $(this).addClass('change').attr('data-content','bar');
});

In CSS:

span.change:after {
    content: attr(data-content) ' any other text you may want';
}

Set CSS property in JavaScript?

Use element.style:

var element = document.createElement('select');
element.style.width = "100px";

Changing CSS pseudo-element styles via JavaScript

EDIT: There is technically a way of directly changing CSS pseudo-element styles via JavaScript, as this answer describes, but the method provided here is preferable.

The closest to changing the style of a pseudo-element in JavaScript is adding and removing classes, then using the pseudo-element with those classes. An example to hide the scrollbar:

CSS

.hidden-scrollbar::-webkit-scrollbar {
   visibility: hidden;
}

JavaScript

document.getElementById("editor").classList.add('hidden-scrollbar');

To later remove the same class, you could use:

document.getElementById("editor").classList.remove('hidden-scrollbar');

Javascript set CSS :after styles

var addRule = (function(style){
    var sheet = document.head.appendChild(style).sheet;
    return function(selector, css){
        var propText = Object.keys(css).map(function(p){
            return p+":"+css[p]
        }).join(";");
        sheet.insertRule(selector + "{" + propText + "}", sheet.cssRules.length);
    }
})(document.createElement("style"));

addRule("p:before", {
    display: "block",
    width: "100px",
    height: "100px",
    background: "red",
    "border-radius": "50%",
    content: "''"
});

A minimal implementation. You most likely would want to keep track of the rules you add so you can remove them. sheet.insertRule returns the index of the new rule which you can use to get a reference to it for editing or removal.

Edit: added basic functionality to convert an object into a css property string for convenience.

modify pseudo select :after in javascript

If that style comes from a CSS file, you'll have to search for it in document.styleSheets, which will be messy.

If you are open to dynamically creating a <style> element containing that CSS instead, you can modify it programmatically.

var slidingTagLiAfterStyle = document.createElement("style");
slidingTagLiAfterStyle.innerHTML =
 ".slidingTag li:after {
    content: '';
    z-index: 3;
    height: 6px;
  }";
document.head.appendChild(slidingTagLiAfterStyle);

...

slidingTagLiAfterStyle.innerHTML = slidingTagLiAfterStyle.innerHTML.replace(/height: [0-9]+px/, "height: 12px"); // or whatever you want to set it to

Apply CSS dynamically with JavaScript

Using Jquery

Use the css() function to apply style to existing elements where you pass an object containing styles :

var styles = {
  backgroundColor : "#ddd",
  fontWeight: ""
};
$("#myId").css(styles);

You can also apply one style at the time with :

$("#myId").css("border-color", "#FFFFFF");

Vanilla JS :

var myDiv = document.getElementById("#myId");
myDiv.setAttribute("style", "border-color:#FFFFFF;");

With Css :

You can also use a separate css file containing the different styles needed inside classes, and depending on the context you add or remove those classes to your elements.

in your css file you can have classes like

.myClass {
    background-color: red;
}

.myOtherClass {
    background-color: blue;
}

Again using jquery, to add or remove a class to an element, you can use

$("#myDiv").addClass('myClass');

or

$("#myDiv").removeClass('myClass');

Again, you can also do the same with vanilla JS:

document.getElementById("#myId").classList.add('myClass') 

or

document.getElementById("#myId").classList.remove('myClass') 

I think this is a cleaner way as it separates your style from your logic. But if the values of your css depends from what is returned by the server, this solution might be difficult to apply.

Dynamically styling pseudo-elements using jQuery or Javascript

May I suggest doing like this, where you dynamically create a style element (with a unique id so you can access it over and over) and just update a rule repeatedly

Usage

loadStyle('p.clicker::after { margin-top: ' + calculated-value + 'px; }');

Script

function loadStyle(css) {
  var style = document.querySelector('style[id="lastinbody"]') || document.createElement('style');
  style.id = 'lastinbody';
  style.type = 'text/css';
  if (style.styleSheet){
    style.styleSheet.cssText = css;
  } else {
    style.appendChild(document.createTextNode(css));
  }
  document.querySelector('body').appendChild(style);
}

---

At this post of mine is a few more versions (which might be consider as a possible duplicate)

---

Related Topics