How do you add CSS with Javascript?
You can also do this using DOM Level 2 CSS interfaces (MDN):
var sheet = window.document.styleSheets[0];
sheet.insertRule('strong { color: red; }', sheet.cssRules.length);
...on all but (naturally) IE8 and prior, which uses its own marginally-different wording:
sheet.addRule('strong', 'color: red;', -1);
There is a theoretical advantage in this compared to the createElement-set-innerHTML method, in that you don't have to worry about putting special HTML characters in the innerHTML, but in practice style elements are CDATA in legacy HTML, and ‘<’ and ‘&’ are rarely used in stylesheets anyway.
You do need a stylesheet in place before you can started appending to it like this. That can be any existing active stylesheet: external, embedded or empty, it doesn't matter. If there isn't one, the only standard way to create it at the moment is with createElement.
How to dynamically create CSS class in JavaScript and apply?
Here is an option:
var style = document.createElement('style');
style.type = 'text/css';
style.innerHTML = '.cssClass { color: #F00; }';
document.getElementsByTagName('head')[0].appendChild(style);
document.getElementById('someElementId').className = 'cssClass';
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.
How to load up CSS files using Javascript?
Here's the "old school" way of doing it, which hopefully works across all browsers. In theory, you would use setAttribute
unfortunately IE6 doesn't support it consistently.
var cssId = 'myCss'; // you could encode the css path itself to generate id..
if (!document.getElementById(cssId))
{
var head = document.getElementsByTagName('head')[0];
var link = document.createElement('link');
link.id = cssId;
link.rel = 'stylesheet';
link.type = 'text/css';
link.href = 'http://website.example/css/stylesheet.css';
link.media = 'all';
head.appendChild(link);
}
This example checks if the CSS was already added so it adds it only once.
Put that code into a JavaScript file, have the end-user simply include the JavaScript, and make sure the CSS path is absolute so it is loaded from your servers.
VanillaJS
Here is an example that uses plain JavaScript to inject a CSS link into the head
element based on the filename portion of the URL:
<script type="text/javascript">
var file = location.pathname.split( "/" ).pop();
var link = document.createElement( "link" );
link.href = file.substr( 0, file.lastIndexOf( "." ) ) + ".css";
link.type = "text/css";
link.rel = "stylesheet";
link.media = "screen,print";
document.getElementsByTagName( "head" )[0].appendChild( link );
</script>
Insert the code just before the closing head
tag and the CSS will be loaded before the page is rendered. Using an external JavaScript (.js
) file will cause a Flash of unstyled content (FOUC) to appear.
Add CSS to <head> with JavaScript?
As you are trying to add a string of CSS to <head>
with JavaScript?
injecting a string of CSS into a page it is easier to do this with the <link>
element than the <style>
element.
The following adds p { color: green; }
rule to the page.
<link rel="stylesheet" type="text/css" href="data:text/css;charset=UTF-8,p%20%7B%20color%3A%20green%3B%20%7D" />
You can create this in JavaScript simply by URL encoding your string of CSS and adding it the HREF
attribute. Much simpler than all the quirks of <style>
elements or directly accessing stylesheets.
var linkElement = this.document.createElement('link');
linkElement.setAttribute('rel', 'stylesheet');
linkElement.setAttribute('type', 'text/css');
linkElement.setAttribute('href', 'data:text/css;charset=UTF-8,' + encodeURIComponent(myStringOfstyles));
This will work in IE 5.5 upwards
The solution you have marked will work but this solution requires fewer dom operations and only a single element.
How to add CSS properties with JavaScript without style attributes
You can create a style element in DOM and append anything to it which will automatically apply to your element
const appendStyle = (customStyles) => {
const styleEl = document.createElement('style');
styleEl.innterHTML = `yourTagName {${customStyles}}`;
document.body.appendChild(styleEl);
}
appendStyle('background-color: red; font-size: 15');
Set CSS property in JavaScript?
Use element.style
:
var element = document.createElement('select');
element.style.width = "100px";
Add CSS attributes to element with JavaScript
Setting the style attribute like that, overwrites the attribute and removes previously set styles.
What you really should do is set the styles directly instead by changing the style property :
function checkNr(id) {
var elem = document.getElementById(id),
value = elem.value;
if (parseFloat(value) == NaN) {
elem.style.border = '2px solid red';
elem.style.backgroundColor = 'rgb(255, 125, 115)';
} else {
elem.style.border = 'none';
elem.style.backgroundColor = 'rgb(255, 255, 255)';
}
}
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