How do you add CSS with Javascript?

Question

How do you add CSS rules (eg strong { color: red }) by use of Javascript?

Answer 1

Here's a slightly updated version of Chris Herring's solution, taking into account that you can use innerHTML as well instead of a creating a new text node:

function insertCss( code ) {
    var style = document.createElement('style');
    style.type = 'text/css';

    if (style.styleSheet) {
        // IE
        style.styleSheet.cssText = code;
    } else {
        // Other browsers
        style.innerHTML = code;
    }

    document.getElementsByTagName("head")[0].appendChild( style );
}

Answer 2

Shortest One Liner

// One liner function:
const addCSS = s =>(d=>{d.head.appendChild(d.createElement("style")).innerHTML=s})(document);

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

Answer 3

Here's a sample template to help you get started

Requires 0 libraries and uses only javascript to inject both HTML and CSS.

The function was borrowed from the user @Husky above

Useful if you want to run a tampermonkey script and wanted to add a toggle overlay on a website (e.g. a note app for instance)

// INJECTING THE HTML
document.querySelector('body').innerHTML += '<div id="injection">Hello World</div>';

// CSS INJECTION FUNCTION
//https://stackoverflow.com/questions/707565/how-do-you-add-css-with-javascript
function insertCss( code ) {
    var style = document.createElement('style');
    style.type = 'text/css';
    if (style.styleSheet) {
        // IE
        style.styleSheet.cssText = code;
    } else {
        // Other browsers
        style.innerHTML = code;
    }
    document.getElementsByTagName("head")[0].appendChild( style );
}

// INJECT THE CSS INTO FUNCTION
// Write the css as you normally would... but treat it as strings and concatenate for multilines
insertCss(
  "#injection {color :red; font-size: 30px;}" +
  "body {background-color: lightblue;}"
)

Answer 4

Another option is to use JQuery to store the element's in-line style property, append to it, and to then update the element's style property with the new values. As follows:

function appendCSSToElement(element, CssProperties)
        {
            var existingCSS = $(element).attr("style");

             if(existingCSS == undefined) existingCSS = "";

            $.each(CssProperties, function(key,value)
            {
                existingCSS += " " + key + ": " + value + ";";
            });

            $(element).attr("style", existingCSS);

            return $(element);
        }

And then execute it with the new CSS attributes as an object.

appendCSSToElement("#ElementID", { "color": "white", "background-color": "green", "font-weight": "bold" });

This may not necessarily be the most efficient method (I'm open to suggestions on how to improve this. :) ), but it definitely works.

Answer 5

The solution by Ben Blank wouldn't work in IE8 for me.

However this did work in IE8

function addCss(cssCode) {
var styleElement = document.createElement("style");
  styleElement.type = "text/css";
  if (styleElement.styleSheet) {
    styleElement.styleSheet.cssText = cssCode;
  } else {
    styleElement.appendChild(document.createTextNode(cssCode));
  }
  document.getElementsByTagName("head")[0].appendChild(styleElement);
}

Answer 6

This easy example of add <style> in head of html

var sheet = document.createElement('style');
sheet.innerHTML = "table th{padding-bottom: 0 !important;padding-top: 0 !important;}\n"
+ "table ul {    margin-top: 0 !important;    margin-bottom: 0 !important;}\n"
+ "table td{padding-bottom: 0 !important;padding-top: 0 !important;}\n"
+ ".messages.error{display:none !important;}\n"
+ ".messages.status{display:none !important;} ";

document.body.appendChild(sheet); // append in body
document.head.appendChild(sheet); // append in head

Source Dynamic style - manipulating CSS with JavaScript