The only browser to support the BroadcastChannel API is Firefox 38 (at the time of writing this) which isn’t slated for release until May, 2015. If you are using Firefox Developer Edition, then you already have support for the BroadcastChannel API and you can start playing around with it now.
This new API opens up a world of possibilities, working around inherent limitations in the existing postMessage API we already have. The BroadcastChannel API is part of the WHATWG living HTML standard which can be seen here.
With HTML5 came a plethora of useful API’s and added methods, one of those which didn’t really get as much visibility (ha, get it?) was the Page Visibility API.
What is the Page Visibility API? The clue is in the name. It allows you to determine if a page is visible (a tab is focused or window being shown). Historically we haven’t really been able to reliably determine if a visitor is looking at a page and as such, can cause issues when media is being played.
Since the recent announcement of HTML5 being finalised, we can finally talk about all of the awesome additions to HTML5 without fear of them changing. Once such addition to HTML5 is the FileReader API which allows you to work with files locally on a hard drive.
The FileReader API is seriously undervalued and surprisingly a few developers I have spoken with who know about it, have not used it or assumed that it was not really supported and thus, ignored it. And some others have not heard about it at all.
If you answered yes, you have just found the solution. Keep on reading.
If you are new to styling placeholder text or perhaps have just not noticed, Firefox in version 19 and beyond by default applies an opacity of 40% (0.4) to placeholder text, as per the documentation.
While I have known about this particular caveat for a while, it turns out a lot of developers who I have asked were not aware that this happens. So next time you change the colour of placeholder text in Firefox, set the opacity to 1 and you should be fine.