Change CSS class properties with jQuery
JqueryCssAjaxClassPropertiesJquery Problem Overview
Is there a way to change the properties of a CSS class, not the element properties, using jQuery?
This is a practical example:
I have a div with class red
.red {background: red;}
I want to change class red background property, not elements that have class red background assigned.
If I do it with jQuery .css() method:
$('.red').css('background','green');
it will affect the elements that right now have class red. Up to here everything is fine.
But if I make an Ajax call, and insert more divs with red class, those won't have a green background, they will have the initial red background.
I could call jQuery .css() method again. But I would like to know if there is a way to change the class itself. Please consider this is just a basic example.
Jquery Solutions
Solution 1 - Jquery
You can't change CSS properties directly with jQuery. But you can achieve the same effect in at least two ways.
Dynamically Load CSS from a File
function updateStyleSheet(filename) {
newstylesheet = "style_" + filename + ".css";
if ($("#dynamic_css").length == 0) {
$("head").append("<link>")
css = $("head").children(":last");
css.attr({
id: "dynamic_css",
rel: "stylesheet",
type: "text/css",
href: newstylesheet
});
} else {
$("#dynamic_css").attr("href",newstylesheet);
}
}
The example above is copied from:
Dynamically Add a Style Element
$("head").append('<style type="text/css"></style>');
var newStyleElement = $("head").children(':last');
newStyleElement.html('.red{background:green;}');
The example code is copied from this JSFiddle fiddle originally referenced by Alvaro in their comment.
Solution 2 - Jquery
In case you cannot use different stylesheet by dynamically loading it, you can use this function to modify CSS class. Hope it helps you...
function changeCss(className, classValue) {
// we need invisible container to store additional css definitions
var cssMainContainer = $('#css-modifier-container');
if (cssMainContainer.length == 0) {
var cssMainContainer = $('<div id="css-modifier-container"></div>');
cssMainContainer.hide();
cssMainContainer.appendTo($('body'));
}
// and we need one div for each class
classContainer = cssMainContainer.find('div[data-class="' + className + '"]');
if (classContainer.length == 0) {
classContainer = $('<div data-class="' + className + '"></div>');
classContainer.appendTo(cssMainContainer);
}
// append additional style
classContainer.html('<style>' + className + ' {' + classValue + '}</style>');
}
This function will take any class name and replace any previously set values with the new value. Note, you can add multiple values by passing the following into classValue: "background: blue; color:yellow".
Solution 3 - Jquery
Didn't find the answer I wanted, so I solved it myself:
modify a container div!
<div class="rotation"> <!-- Set the container div's css -->
<div class="content" id='content-1'>This div gets scaled on hover</div>
</div>
<!-- Since there is no parent here the transform doesnt have specificity! -->
<div class="rotation content" id='content-2'>This div does not</div>
css you want to persist after executing $target.css()
.content:hover {
transform: scale(1.5);
}
modify content's containing div with css()
$(".rotation").css("transform", "rotate(" + degrees + "deg)");
[Codepen example][1]
[1]: http://codepen.io/chyde/pen/RrWJam "codepen example"
Solution 4 - Jquery
You can remove classes and add classes dynamically
$(document).ready(function(){
$('#div').removeClass('left').addClass('right');
});
Solution 5 - Jquery
$(document)[0].styleSheets[styleSheetIndex].insertRule(rule, lineIndex);
styleSheetIndex is the index value that corresponds to which order you loaded the file in the <head> (e.g. 0 is the first file, 1 is the next, etc. if there is only one CSS file, use 0).
rule is a text string CSS rule. Like this: "body { display:none; }".
lineIndex is the line number in that file. To get the last line number, use $(document)[0].styleSheets[styleSheetIndex].cssRules.length. Just console.log that styleSheet object, it's got some interesting properties/methods.
Because CSS is a "cascade", whatever rule you're trying to insert for that selector you can just append to the bottom of the CSS file and it will overwrite anything that was styled at page load.
In some browsers, after manipulating the CSS file, you have to force CSS to "redraw" by calling some pointless method in DOM JS like document.offsetHeight (it's abstracted up as a DOM property, not method, so don't use "()") -- simply adding that after your CSSOM manipulation forces the page to redraw in older browsers.
So here's an example:
stylesheet.insertRule('body { display:none; }', stylesheet.cssRules.length);```
Solution 6 - Jquery
You can add a class to the parent of the red div, e.g. green-style
$('.red').parent().addClass('green-style');
then add style to the css
.green-style .red {
background:green;
}
so everytime you add red element under green-style, the background will be green
Solution 7 - Jquery
Here's a bit of an improvement on the excellent answer provided by Mathew Wolf. This one appends the main container as a style tag to the head element and appends each new class to that style tag. a little more concise and I find it works well.
function changeCss(className, classValue) {
var cssMainContainer = $('#css-modifier-container');
if (cssMainContainer.length == 0) {
var cssMainContainer = $('<style id="css-modifier-container"></style>');
cssMainContainer.appendTo($('head'));
}
cssMainContainer.append(className + " {" + classValue + "}\n");
}
Solution 8 - Jquery
You may want to take a different approach: Instead of changing the css dynamically, predefine your styles in CSS the way you want them. Then use JQuery to add and remove styles from within Javascript. (see code from Ajmal)