I have a web application that's branded according to the user that's currently logged in. I'd like to change the favicon of the page to be the logo of the private label, but I'm unable to find any code or any examples of how to do this. Has anybody successfully done this before?
I'm picturing having a dozen icons in a folder, and the reference to which favicon.ico file to use is just generated dynamically along with the HTML page. Thoughts?
Here’s some code that works in Firefox, Opera, and Chrome (unlike every other answer posted here). Here is a different demo of code that works in IE11 too. The following example might not work in Safari or Internet Explorer.
/*!
* Dynamically changing favicons with JavaScript
* Works in all A-grade browsers except Safari and Internet Explorer
* Demo: http://mathiasbynens.be/demo/dynamic-favicons
*/
// HTML5™, baby! http://mathiasbynens.be/notes/document-head
document.head = document.head || document.getElementsByTagName('head')[0];
function changeFavicon(src) {
var link = document.createElement('link'),
oldLink = document.getElementById('dynamic-favicon');
link.id = 'dynamic-favicon';
link.rel = 'shortcut icon';
link.href = src;
if (oldLink) {
document.head.removeChild(oldLink);
}
document.head.appendChild(link);
}
You would then use it as follows:
var btn = document.getElementsByTagName('button')[0];
btn.onclick = function() {
changeFavicon('http://www.google.com/favicon.ico');
};
Fork away or view a demo.
If you have the following HTML snippet:
<link id="favicon" rel="shortcut icon" type="image/png" href="favicon.png" />
You can change the favicon using Javascript by changing the HREF element on this link, for instance (assuming you're using JQuery):
$("#favicon").attr("href","favicon2.png");
You can also create a Canvas element and set the HREF as a ToDataURL() of the canvas, much like the Favicon Defender does.
jQuery Version:
$("link[rel='shortcut icon']").attr("href", "favicon.ico");
or even better:
$("link[rel*='icon']").attr("href", "favicon.ico");
Vanilla JS version:
document.querySelector("link[rel='shortcut icon']").href = "favicon.ico";
document.querySelector("link[rel*='icon']").href = "favicon.ico";
A more modern approach:
const changeFavicon = link => {
let $favicon = document.querySelector('link[rel="icon"]')
// If a <link rel="icon"> element already exists,
// change its href to the given link.
if ($favicon !== null) {
$favicon.href = link
// Otherwise, create a new element and append it to <head>.
} else {
$favicon = document.createElement("link")
$favicon.rel = "icon"
$favicon.href = link
document.head.appendChild($favicon)
}
}
You can then use it like this:
changeFavicon("http://www.stackoverflow.com/favicon.ico")
Here's some code I use to add dynamic favicon support to Opera, Firefox and Chrome. I couldn't get IE or Safari working though. Basically Chrome allows dynamic favicons, but it only updates them when the page's location (or an iframe etc in it) changes as far as I can tell:
var IE = navigator.userAgent.indexOf("MSIE")!=-1
var favicon = {
change: function(iconURL) {
if (arguments.length == 2) {
document.title = optionalDocTitle}
this.addLink(iconURL, "icon")
this.addLink(iconURL, "shortcut icon")
// Google Chrome HACK - whenever an IFrame changes location
// (even to about:blank), it updates the favicon for some reason
// It doesn't work on Safari at all though :-(
if (!IE) { // Disable the IE "click" sound
if (!window.__IFrame) {
__IFrame = document.createElement('iframe')
var s = __IFrame.style
s.height = s.width = s.left = s.top = s.border = 0
s.position = 'absolute'
s.visibility = 'hidden'
document.body.appendChild(__IFrame)}
__IFrame.src = 'about:blank'}},
addLink: function(iconURL, relValue) {
var link = document.createElement("link")
link.type = "image/x-icon"
link.rel = relValue
link.href = iconURL
this.removeLinkIfExists(relValue)
this.docHead.appendChild(link)},
removeLinkIfExists: function(relValue) {
var links = this.docHead.getElementsByTagName("link");
for (var i=0; i<links.length; i++) {
var link = links[i]
if (link.type == "image/x-icon" && link.rel == relValue) {
this.docHead.removeChild(link)
return}}}, // Assuming only one match at most.
docHead: document.getElementsByTagName("head")[0]}
To change favicons, just go favicon.change("ICON URL") using the above.
(credits to http://softwareas.com/dynamic-favicons for the code I based this on.)
Here's a snippet to make the favicon be an emoji, or text. It works in the console when I'm at stackoverflow.
function changeFavicon(text) {
const canvas = document.createElement('canvas');
canvas.height = 64;
canvas.width = 64;
const ctx = canvas.getContext('2d');
ctx.font = '64px serif';
ctx.fillText(text, 0, 64);
const link = document.createElement('link');
const oldLinks = document.querySelectorAll('link[rel="shortcut icon"]');
oldLinks.forEach(e => e.parentNode.removeChild(e));
link.id = 'dynamic-favicon';
link.rel = 'shortcut icon';
link.href = canvas.toDataURL();
document.head.appendChild(link);
}
changeFavicon('❤️');
I would use Greg's approach and make a custom handler for favicon.ico Here is a (simplified) handler that works:
using System;
using System.IO;
using System.Web;
namespace FaviconOverrider
{
public class IcoHandler : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
context.Response.ContentType = "image/x-icon";
byte[] imageData = imageToByteArray(context.Server.MapPath("/ear.ico"));
context.Response.BinaryWrite(imageData);
}
public bool IsReusable
{
get { return true; }
}
public byte[] imageToByteArray(string imagePath)
{
byte[] imageByteArray;
using (FileStream fs = new FileStream(imagePath, FileMode.Open, FileAccess.Read))
{
imageByteArray = new byte[fs.Length];
fs.Read(imageByteArray, 0, imageByteArray.Length);
}
return imageByteArray;
}
}
}
Then you can use that handler in the httpHandlers section of the web config in IIS6 or use the 'Handler Mappings' feature in IIS7.
The only way to make this work for IE is to set you web server to treat requests for *.ico to call your server side scripting language (PHP, .NET, etc). Also setup *.ico to redirect to a single script and have this script deliver the correct favicon file. I'm sure there is still going to be some interesting issues with cache if you want to be able to bounce back and forth in the same browser between different favicons.
According to WikiPedia, you can specify which favicon file to load using the link tag in the head section, with a parameter of rel="icon".
For example:
<link rel="icon" type="image/png" href="/path/image.png">
I imagine if you wanted to write some dynamic content for that call, you would have access to cookies so you could retrieve your session information that way and present appropriate content.
You may fall foul of file formats (IE reportedly only supports it's .ICO format, whilst most everyone else supports PNG and GIF images) and possibly caching issues, both on the browser and through proxies. This would be because of the original itention of favicon, specifically, for marking a bookmark with a site's mini-logo.
Yes totally possible
e.g.
<link rel="shortcut icon" href="/favicon.ico?userId=someUserId">
Then whatever server side language / framework you use should easily be able to find the file based on the userId and serve it up in response to that request.
But to do favicons properly (its actually a really complex subject) please see the answer here https://stackoverflow.com/a/45301651/661584
A lot lot easier than working out all the details yourself.
Enjoy.
I use this feature all the time when developing sites ... so I can see at-a-glance which tab has local, dev or prod running in it.
Now that Chrome supports SVG favicons it makes it a whole lot easier.
Have a gander at https://gist.github.com/elliz/bb7661d8ed1535c93d03afcd0609360f for a tampermonkey script that points to a demo site I chucked up at https://elliz.github.io/svg-favicon/
Adapted this from another answer ... could be improved but good enough for my needs.
(function() {
'use strict';
// play with https://codepen.io/elliz/full/ygvgay for getting it right
// viewBox is required but does not need to be 16x16
const svg = `
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16">
<circle cx="8" cy="8" r="7.2" fill="gold" stroke="#000" stroke-width="1" />
<circle cx="8" cy="8" r="3.1" fill="#fff" stroke="#000" stroke-width="1" />
</svg>
`;
var favicon_link_html = document.createElement('link');
favicon_link_html.rel = 'icon';
favicon_link_html.href = svgToDataUri(svg);
favicon_link_html.type = 'image/svg+xml';
try {
let favicons = document.querySelectorAll('link[rel~="icon"]');
favicons.forEach(function(favicon) {
favicon.parentNode.removeChild(favicon);
});
const head = document.getElementsByTagName('head')[0];
head.insertBefore( favicon_link_html, head.firstChild );
}
catch(e) { }
// functions -------------------------------
function escapeRegExp(str) {
return str.replace(/([.*+?^=!:${}()|\[\]\/\\])/g, "\\$1");
}
function replaceAll(str, find, replace) {
return str.replace(new RegExp(escapeRegExp(find), 'g'), replace);
}
function svgToDataUri(svg) {
// these may not all be needed - used to be for uri-encoded svg in old browsers
var encoded = svg.replace(/\s+/g, " ")
encoded = replaceAll(encoded, "%", "%25");
encoded = replaceAll(encoded, "> <", "><"); // normalise spaces elements
encoded = replaceAll(encoded, "; }", ";}"); // normalise spaces css
encoded = replaceAll(encoded, "<", "%3c");
encoded = replaceAll(encoded, ">", "%3e");
encoded = replaceAll(encoded, "\"", "'"); // normalise quotes ... possible issues with quotes in <text>
encoded = replaceAll(encoded, "#", "%23"); // needed for ie and firefox
encoded = replaceAll(encoded, "{", "%7b");
encoded = replaceAll(encoded, "}", "%7d");
encoded = replaceAll(encoded, "|", "%7c");
encoded = replaceAll(encoded, "^", "%5e");
encoded = replaceAll(encoded, "`", "%60");
encoded = replaceAll(encoded, "@", "%40");
var dataUri = 'data:image/svg+xml;charset=UTF-8,' + encoded.trim();
return dataUri;
}
})();
Just pop your own SVG (maybe cleaned with Jake Archibald's SVGOMG if you're using a tool) into the const at the top. Make sure it is square (using the viewBox attribute) and you're good to go.
I use favico.js in my projects.
It allows to change the favicon to a range of predefined shapes and also custom ones.
Internally it uses canvas for rendering and base64 data URL for icon encoding.
The library also has nice features: icon badges and animations; purportedly, you can even stream the webcam video into the icon :)
