All of the major browsers except Internet Explorer (including IE9) support Web Workers today.
HTML5 iFrames In almost all cases, progress on the Web is marked by bold strides forward with new features that enable wonderful code to be written in fewer and cleaner lines. One exception is the <iframe> tag in HTML5, a rare case of a tag that's losing some features. Don't worry, though, or start to feel claustrophobic. The functionality is merely being moved to make the integration of the iframe more seamless.
In the past, the Web designer could add scroll bars, borders, and margins to the content embedded in the iframe. Now all of that work has to be done by the HTML of the iframe itself. The Web designer coding the iframe won't have these options any longer.
That designer does get a few new options. The "seamless" attribute removes any of the borders and scroll bars, rendering the iframe like a <div> tag that acquires its information from another source.
The other option will comfort those who worry about the security of their Web pages. The "sandbox" attribute turns off many of the more dangerous features sometimes given to content inside the iframe. The main page's author needs to explicitly enable them by adding attributes such as "allow-scripts" or "allow-forms."
These new iframe attributes are useful features that will make it easier for Web page designers to collaborate with other sites, yet not worry as much about dangerous behavior. Advertisers who create more interactive campaigns will love these options because they let websites adopt the ads while providing enough security to block wayward behavior. Websites won't need to trust the ad companies as they do now.
HTML5 Parsing No specification is ever complete because no one can even begin to imagine all of the ways that someone will use it. Over the years, the browser programmers have been surprised again and again by the ways that HTML writers found new and unexpected ways to use the tags. In the most glaring cases, the HTML creators unearthed spots where the browser developers made different assumptions. The HTML5 specification tries to spell out these places and smooth over the differences.
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