Rendering HTML5 in older browsers with Google Chrome Frame

发布于 2023-10-02 10:17:49 字数 7954 浏览 29 评论 0

HTML5 adds a multitude of new awesome tools to the web developer toolbox, including the following:

New, more powerful JavaScript APIs
SVG for vector graphics
Canvas for 2D and with WebGL 3D graphics
CSS3 for rounded corners, gradients, etc.
More expressive markup

This list is, of course, not comprehensive; the web platform has moved forward massively, and the gap between old browsers and modern ones is widening every day.
Every major desktop browser now supports significant parts of HTML5 in the latest version but old browsers sticking around create a challenge for adopting the latest and greatest features today.

Google Chrome Frame can help you build state-of-the-art HTML5 pages today while still enabling people using older browsers to see your content.

What is Google Chrome Frame

Google Chrome Frame is a plugin for Internet Explorer that enables rendering the full browser canvas using Google Chrome’s rendering engine. It supports all the HTML5 features that you find in Chrome seamlessly integrated into the Internet Explorer user experience. Chrome Frame is available for Internet Explorer 6, 7, 8, and 9. Chrome Frame is certainly more useful when supporting old browser such as IE6-to-IE8 but if you, for example, require WebGL for your application, requiring Chrome Frame for IE9 users might be useful as well.

HTML5 polyfills provide another way to smooth out the transition to newer browsers. Unfortunately, they cannot emulate every feature, and they slow down your page in old browsers, which are already slower that the new generation, even more.

Even if your site does not need HTML5 features, using Chrome Frame could still provide a better user experience. For users who already have it installed, rendering is generally faster and they can get access to features that are not supported in older browsers. You can, of course, still decide to support old browsers for users who do not have Chrome Frame on their machine.

Opting in

You can enable Chrome Frame to render a page by adding an HTML metatag or using an HTTP header. This is very important. It means no site will break if a user has Chrome Frame installed, because the site is in full control of using the plugin or default rendering. The following code snippets show how a site can opt into being rendered by Chrome Frame.

Option 1: HTTP-Header (you can add this to your HTTP server (e.g. Apache) configuration) :

X-UA-Compatible: chrome=1

Option 2: Meta-tag (Just paste this into your HTML <head> section)

<meta http-equiv="X-UA-Compatible" content="chrome=1">

Once you have added either one of these to your site, pages are rendered using Chrome Frame if it is installed on the user’s machine.

Prompting for Google Chrome Frame

You may decide to fully deprecate support for old browsers for many reasons including the following:

Your site requires modern features such as HTML5 video, canvas, WebGL, or CSS3
Development time spent on old browsers is too high
Speed up development time for new features

Chrome Frame might provide a strategy to continue giving users of old browsers a way to still use your site.

Chrome Frame transmits that it is available by extending the host's User-Agent header with the string "chromeframe". For more information see Chrome Frame User Agent.

Use server-side detection to look for this token and determine whether Chrome Frame can be used for a page. If Chrome Frame is present, you can insert the required meta tag; if not, you can redirect users to a page that explains how to install Chrome Frame. As an alternative to server-side sniffing, you can use the CFInstall.js script to detect Chrome Frame and prompt users to install the plug-in without restarting their browsers. Using the script is straightforward. Just add the script tags and optional styles to your page as in the following example:

<html>
<body>
 <script type="text/javascript"
  src="http://ajax.googleapis.com/ajax/libs/chrome-frame/1/CFInstall.min.js"></script>

 <style>
  /*
   CSS rules to use for styling the overlay:
     .chromeFrameOverlayContent
     .chromeFrameOverlayContent iframe
     .chromeFrameOverlayCloseBar
     .chromeFrameOverlayUnderlay
  */
 </style>

 <script>
   // You may want to place these lines inside an onload handler
  CFInstall.check({
    mode: "overlay",
    destination: "http://www.waikiki.com"
  });
 </script>
</body>
</html>

Prompt yourself

You might also decide to build a landing page or layer yourself. Send users to this URL
http://www.google.com/chromeframe/ which can be put in an IFRAME.
Append a redirect parameter to send users back to your site after installation is complete:
http://www.google.com/chromeframe/?redirect=http://www.google.com/
Instead of going to the Chrome Frame landing page, you could also send the users directly to the EULA thus saving one step in the installation process.
http://www.google.com/chromeframe/eula.html

No admin-rights needed

Users can install Chrome Frame without having administrative privileges on their machines.
Append the user=true parameter to enable user level installation of Chrome Frame, as in the following:
http://www.google.com/chromeframe/?user=true

Enterprise installation

Enterprises can deploy Chrome Frame company wide using the MSI installer which can be downloaded here: http://www.google.com/chromeframe/eula.html?msi=true .
For more information on Chrome and enterprise deployments see http://www.chromium.org/administrators .

Adoption

Many major websites such as yahoo.com , wordpress.com and several Google properties have adopted Google Chrome Frame. Besides giving their users access to a more modern web experience for many sites, Chrome Frame also presents a significant improvement in initial load time. You can check whether Chrome Frame helps your site get faster rendering by going to webpagetest.org and selecting Chrome Frame as the browser.