ECMAScript version 5 covers a large number of feature additions to what we normally call JavaScript. Excluding IE8, most of ES5 is supported in browsers. As it introduces no new syntax, it's possible to polyfill fairly well. The below polyfills tackle most uses of these features, but not all cases.
+ECMAScript version 5 covers a large number of feature additions to what we normally call JavaScript. +Excluding IE8, most of ES5 is supported in browsers. +As it introduces no new syntax, it's possible to polyfill fairly well. +The below polyfills tackle most uses of these features, but there is an unshimmable subset of ES5. +Also note that some shims are known to have edgecase compliance bugs.
Use the Font Squirrel Generator for fonts you have license for using as web fonts. Font Squirrel @font-face syntax is also the most bullet-proof way of serving web fonts. You do not need polyfills - just fonts in several formats; WOFF is preferred, followed by TTF and then EOT.
+Use the Font Squirrel Generator for fonts you have license for using as web fonts. Fontspring @font-face syntax is also the most bullet-proof way of serving web fonts. You do not need polyfills - just fonts in several formats; WOFF is preferred, followed by TTF and then EOT.
Also, don't use sIFR or Cufon anymore.
HTML5 has baked in clientside form validation, and polyfills can enable this for legacy browsers as well. Using the defined HTML5 API for constraint validation may be a more maintainable direction than using a jQuery Validation plugin, depending on your team.
++ + + View browser share % + + + Edit this info +
+Input placeholders are simply ignored in IE 9 and below. Note that they are only applied when the type of the input is text, search, tel, url, or email. Otherwise, it is ignored.
+ +input[placeholder] is commonly the first polyfill anyone writes and, as such, there are many of them. Password inputs and submit event clearing are among many of the gotchas that catch naïve implemenations; Mathias's polyfill below handles these cases very well.
+ + + View browser share % + + + Edit this info +
+Color inputs will fall back to a plain text input if it's not supported, but excluding Opera, no desktop browser has added support for color inputs.
+ +You should probably avoid this until it has support in WebKit, Gecko or IE.
++ + + View browser share % + + + Edit this info +
+There are many date inputs: datetime-local, date, time, month, week that should provide a datepicker to the user. For a long time, WebKit offered a spinner UI on these inputs, but this was an incomplete implementation (and has since been removed).
A few polyfills offer a proper datepicker UI, if the feature is not offered natively.
+ +We suggest you use Modernizr to detect this feature, as it has correctly detected these features, regardless of WebKit's partial implementation or other browser bugs.
++ + + View browser share % + + + Edit this info +
+Range inputs (AKA sliders) will fall back to a plain text input if it's not supported.
+ +You can use freqdec's Input Range Polyfill or for just Firefox support, Frank Yan's html5slider.
+ +These polyfills aren't drop-in polyfills and you'll need to wire them up a little, but your markup can depend on <input type=range> creating a slider.
+ + + View browser share % + + + Edit this info +
+Internet Explorer, and Opera support CSS Multiple Column without vendor prefixes, so you only need prefixed versions for -webkit and -moz. We recommend you do not polyfill this and let it fall back to single column text.
Internet Explorer (10+), and Opera support CSS Multiple Column without vendor prefixes, so you only need prefixed versions for -webkit and -moz. A further note, features like column-break-after, column-break-before, and column-break-inside which are necessary for advanced typography are webkit-only right now.
We recommend you do not polyfill this and let it fall back to single column text.
Input placeholders are simply ignored in IE 9 and below. Note that they are only applied when the type of the input is text, search, tel, url, or email. Otherwise, it is ignored.
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-Making your app real-time is a huge boost and Socket.io is a Node+Javascript framework that helps with downlevel transports for browsers lacking native websocket support (and supports IE6+). However be prepared to tune your AJAX polling or Comet in order to meet the needs of your app.
+Making your app real-time is a huge boost and Socket.io is a Node+JavaScript framework that helps with downlevel transports for browsers lacking native WebSocket support (and supports IE6+). However be prepared to tune your AJAX polling or Comet in order to meet the needs of your app.
-web-socket-js is a natural polyfill for the Javascript WebSocket API transferring data through Flash Sockets when WebSockets aren't available.
+web-socket-js is a natural polyfill for the JavaScript WebSocket API transferring data through Flash Sockets when WebSockets aren't available.
-As a word of caution, the protocol backing the Web Socket API has become an IETF standard, but Safari has not yet implemented the new version. It is recommended forcing Flash on Safari (or disabling WebSockets on Safari) for now.
+As a word of caution, the protocol backing the Web Socket API has become an IETF standard, but Safari has not yet implemented the new version. It is recommended forcing Flash on Safari (if Flash is available, N/A on mobile), or disabling WebSockets on Safari for now.