Add CSS to <head> with JavaScript?

Question

Is there a way to add css from a string in the javascript file to the head of a document with javascript?

Let's say we have a webpage, which has a lightbox script, this script requires a css file to function.

Now adding this css file with <link> will make the css file download even for people that don't have js enabled.

I know that I can dynamically load the css file with the script, but that also means that there will be 2 http requests, and in cases where there is little to no css in the file I find this inefficient.

So I thought to myself, what if you could put the css that you have in the css file, into the script, have the script parse the css and add it into the head, or even better just have the script add the css directly into the <head> of the document.

But I have found nothing online that suggests that this is possible, so is it possible to add css to the head with js?

Edit + SOLUTION:

I edited roryf's answer to work cross browser (except IE5)

Javascript:

 function addcss(css){
    var head = document.getElementsByTagName('head')[0];
    var s = document.createElement('style');
    s.setAttribute('type', 'text/css');
    if (s.styleSheet) {   // IE
        s.styleSheet.cssText = css;
    } else {                // the world
        s.appendChild(document.createTextNode(css));
    }
    head.appendChild(s);
 }

Have a look at the following link .. It explains every little details about your question ... and it is named appropriately Totally Pwn CSS with Javascript — Gabriele Petrioli
– Gabriele Petrioli, Commented Oct 13, 2010 at 9:07

Timo Huovinen · Accepted Answer · 2022-03-13 17:50:46Z

46

Edit: As Atspulgs comment suggest, you can achieve the same without jQuery using the querySelector:

document.head.innerHTML += '<link rel="stylesheet" href="styles.css" type="text/css"/>';

Older answer below.

You could use the jQuery library to select your head element and append HTML to it, in a manner like:

$('head').append('<link rel="stylesheet" href="style2.css" type="text/css" />');

You can find a complete tutorial for this problem here

edited Mar 13, 2022 at 17:50

Timo Huovinen

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answered Oct 13, 2010 at 9:08

thomaux

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3 Comments

TRiG Over a year ago

Again, this method loads a new file, which Yuri wanted to avoid. Also, loading the entire jQuery library for something as simple as this is rather silly.

Atspulgs Over a year ago

without jQuery: document.querySelector('head').innerHTML += '<link rel="stylesheet" href="styles.css" type="text/css"/>';

Iharob Al Asimi Over a year ago

document.head, is the head element!

moefinley · Accepted Answer · 2019-02-08 20:01:28Z

34

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.

edited Feb 8, 2019 at 20:01

answered Apr 19, 2018 at 14:50

moefinley

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8 Comments

Jānis Elmeris Over a year ago

let linkElement: HTMLLinkElement = this.document.createElement('link'); will work in IE 5.5, you say?

Bogdan M. Over a year ago

@JānisElmeris if you use javascript with the syntax used by the ie it will. createElement and setAttribute are not new methods.

Jānis Elmeris Over a year ago

@BogdanM., well, I just expect code described as "this will work in ..." to actually already have the proper syntax.

Hex Over a year ago

let linkElement: HTMLLinkElement = ... - what's this syntax called?

moefinley Over a year ago

Sorry, that's a Typescript type. It shouldn't really be in there.

|

Jeriko · Accepted Answer · 2010-10-14 09:04:19Z

27

If you don't want to rely on a javascript library, you can use document.write() to spit out the required css, wrapped in style tags, straight into the document head:

<head>
  <script type="text/javascript">
    document.write("<style>body { background-color:#000 }</style>");
  </script>
  # other stuff..
</head>

This way you avoid firing an extra HTTP request.

There are other solutions that have been suggested / added / removed, but I don't see any point in overcomplicating something that already works fine cross-browser. Good luck!

http://jsbin.com/oqede3/edit

edited Oct 14, 2010 at 9:04

answered Oct 13, 2010 at 9:10

Jeriko

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16 Comments

Tim Down Over a year ago

That's fine until you want to add a CSS rule after the document has rendered.

Jeriko Over a year ago

Good thing OP doesn't have that requirement then! Your solution covers that, but imho it's totally overkill for non-js/lightbox css degradation as this.

Tim Down Over a year ago

One thing to note: document.write doesn't work in real XHTML documents, but that's unlikely to be a problem since hardly anyone really uses XHTML.

Timo Huovinen Over a year ago

it's interesting that it works but having style in the body looks a bit hacky :) p.s. you can put the document.write in the head section of the site and it seems to work fine.

Orcra Over a year ago

I would avoid document.write as much as possible.

|

Ally · Accepted Answer · 2018-11-05 10:29:19Z

15

Here's a simple way.

/**
 * Add css to the document
 * @param {string} css
 */
function addCssToDocument(css){
  var style = document.createElement('style')
  style.innerText = css
  document.head.appendChild(style)
}

answered Nov 5, 2018 at 10:29

Ally

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1 Comment

Elijah M Over a year ago

I would use style.textContent

roryf · Accepted Answer · 2010-10-13 15:44:48Z

14

A simple non-jQuery solution, albeit with a bit of a hack for IE:

var css = ".lightbox { width: 400px; height: 400px; border: 1px solid #333}";

var htmlDiv = document.createElement('div');
htmlDiv.innerHTML = '<p>foo</p><style>' + css + '</style>';
document.getElementsByTagName('head')[0].appendChild(htmlDiv.childNodes[1]);

It seems IE does not allow setting innerText, innerHTML or using appendChild on style elements. Here is a bug report which demonstrates this, although I think it identifies the problem incorrectly. The workaround above is from the comments on the bug report and has been tested in IE6 and IE9.

Whether you use this, document.write or a more complex solution will really depend on your situation.

edited Oct 13, 2010 at 15:44

answered Oct 13, 2010 at 9:44

roryf

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9 Comments

Tim Down Over a year ago

Doesn't work in IE. Certainly not 6 or 7, don't have 8 available to test right now. IE doesn't like document.createElement('style').

roryf Over a year ago

@Tim works for me in IE6 and 9, since your solution has the exact same line perhaps you can explain further

Tim Down Over a year ago

@roryf: Oh, yes, you're right, sorry. Foolishly I made the elementary mistake of believing the line number in IE's error. The error's actually in styleElement.innerHTML = css;. Certainly fails in IE 7, retesting in IE 6 now (waiting for VM to come alive).

roryf Over a year ago

@Tim thanks, I suspected that might be a problem, shame on me for not testing properly!

roryf Over a year ago

I couldn't leave this alone so did a bit of research and found a workaround for IE, this should now work cross-browser

|

Tim Down · Accepted Answer · 2010-10-13 09:32:18Z

Here's a function that will dynamically create a CSS rule in all major browsers. createCssRule takes a selector (e.g. "p.purpleText"), a rule (e.g. "color: purple;") and optionally a Document (the current document is used by default):

var addRule;

if (typeof document.styleSheets != "undefined" && document.styleSheets) {
    addRule = function(selector, rule) {
        var styleSheets = document.styleSheets, styleSheet;
        if (styleSheets && styleSheets.length) {
            styleSheet = styleSheets[styleSheets.length - 1];
            if (styleSheet.addRule) {
                styleSheet.addRule(selector, rule)
            } else if (typeof styleSheet.cssText == "string") {
                styleSheet.cssText = selector + " {" + rule + "}";
            } else if (styleSheet.insertRule && styleSheet.cssRules) {
                styleSheet.insertRule(selector + " {" + rule + "}", styleSheet.cssRules.length);
            }
        }
    }
} else {
    addRule = function(selector, rule, el, doc) {
        el.appendChild(doc.createTextNode(selector + " {" + rule + "}"));
    };
}

function createCssRule(selector, rule, doc) {
    doc = doc || document;
    var head = doc.getElementsByTagName("head")[0];
    if (head && addRule) {
        var styleEl = doc.createElement("style");
        styleEl.type = "text/css";
        styleEl.media = "screen";
        head.appendChild(styleEl);
        addRule(selector, rule, styleEl, doc);
        styleEl = null;
    }
};

createCssRule("body", "background-color: purple;");

Very thorough answer, and I believe it will come in handy, but it will be painstaking to take a simple css stylesheet and convert it to this.

NVRM · Accepted Answer · 2021-03-07 13:00:29Z

3

In one call:

document.head.appendChild(Object.assign(document.createElement("style"), {textContent: `
    select, button, input, details, summary { cursor: pointer }
    input { padding: 0.5rem }
    button, select  { margin: 0.5rem }
    @media (max-width:640px) { button  { width: 100% } i {display: block } }
  `
}))

edited Mar 7, 2021 at 13:00

answered Mar 2, 2021 at 1:33

NVRM

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Comments

chickens · Accepted Answer · 2021-12-21 08:02:42Z

1

Shortest One liner:

const addCSS = css => document.head.appendChild(document.createElement("style")).innerHTML = css;

// Usage:
addCSS("body{background:red}");

answered Dec 21, 2021 at 8:02

chickens

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2 Comments

Timo Huovinen Over a year ago

Does it work cross browser?

chickens Over a year ago

It should support all browsers except old IE. I'd appreciate if someone can tell what is the oldest IE version supported.

David Dal Busco · Accepted Answer · 2022-01-14 13:30:53Z

Late to the party, quite similar to all solution but appends only once the script to the head:

export const injectHeadCss = () => {
  let style: HTMLStyleElement | null = document.head.querySelector('style[my-style]');

  if (style !== null) {
    return;
  }

  style = document.createElement('style');
  style.setAttribute('my-style', '');
  style.innerHTML = `
    .class1 {
      background: pink;
    }

    .class2 {
      background: purple;
    }
  `;

  document.head.append(style);
};

K. Kilian Lindberg · Accepted Answer · 2022-02-17 13:10:13Z

Maximizing compatibility, working for most things made 2009-2022 and likely beyond. This solution is intentionally not made with ES6 etc; using an arrow function, let-variable, append (2014) etc.

This short version adds styling to the head-section of a web page and can also be done via the DOM to access the head-section to maximize compatibility further - since querySelector wasn't widely adapted until 2009.

Note that innerHTML / write nowadays isn't recommended for production.

Just copy+paste it into the console to try it out and a page like this gets some nice additions;

function ahsf(styling){ document.querySelector('head').innerHTML+="<style>"+ styling +"</style>";}
//Called with
ahsf(" * { border: 1px dashed #f09 !important; } ");

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