下面是一个片段，使favicon成为一个表情符号或文本。当我在stackoverflow时，它在控制台工作。

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('❤️');

在开发网站时，我一直在使用这个功能……这样我就可以一目了然地看到哪个选项卡有本地，开发或刺激运行在它。

现在Chrome支持SVG favicons，这让它变得更容易了。

篡改猴脚本

在https://gist.github.com/elliz/bb7661d8ed1535c93d03afcd0609360f上查看tampermonkey脚本，该脚本指向我在https://elliz.github.io/svg-favicon/上抛出的演示站点

基本代码

改编自另一个答案…可以改进，但足以满足我的需求。

(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;
    }

})();

只需将您自己的SVG(如果使用工具，可以使用Jake Archibald的SVGOMG清洗)放入顶部的const。确保它是正方形的(使用viewBox属性)，然后就可以开始了。

我会使用Greg的方法，为favicon.ico创建一个自定义处理程序 下面是一个(简化的)处理程序:

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;
    }
    }
}

然后你可以在IIS6的web配置的httpHandlers部分使用该处理程序，或者在IIS7中使用' handler Mappings'特性。

对于那些使用jQuery的人来说，有一个单行解决方案:

$("link[rel*='icon']").prop("href",'https://www.stackoverflow.com/favicon.ico');

下面是一些可以在Firefox, Opera和Chrome上运行的代码(不同于这里发布的其他答案)。下面是一个在IE11中也能运行的不同代码演示。下面的示例可能无法在Safari或Internet Explorer中运行。

/*!
 * 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);
}

然后你可以这样使用它:

var btn = document.getElementsByTagName('button')[0];
btn.onclick = function() {
 changeFavicon('http://www.google.com/favicon.ico');
};

叉子或查看演示。

下面是我用来为Opera、Firefox和Chrome添加动态图标支持的一些代码。不过我无法让IE或Safari正常工作。基本上Chrome允许动态favicons，但只有当页面的位置(或iframe等)发生变化时才会更新它们:

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]}

要更改favicon，只需访问favicon。更改("ICON URL")使用上述。

(我基于http://softwareas.com/dynamic-favicons的代码。)