perf_alert

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Recent Features

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    Page Visibility API

    One event that's always been lacking within the document is a signal for when the user is looking at a given tab, or another tab. When does the user switch off our site to look at something else? When do they come back?

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    JavaScript Promise API

    While synchronous code is easier to follow and debug, async is generally better for performance and flexibility. Why "hold up the show" when you can trigger numerous requests at once and then handle them when each is ready?  Promises are becoming a big part of the JavaScript world...

Incredible Demos

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    CSS calc

    CSS is a complete conundrum; we all appreciate CSS because of its simplicity but always yearn for the language to do just a bit more. CSS has evolved to accommodate placeholders, animations, and even click events. One problem we always thought...

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    Chris Coyier’s Favorite CodePen Demos IV

    Did you know you can triple-heart things on CodePen? We’ve had that little not-so-hidden feature forever. You can click that little heart button on any Pen (or Project, Collection, or Post) on CodePen to show the creator a little love, but you can click it again...

Discussion

    Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!