Re: test for autoplay

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From	Thomas 'PointedEars' Lahn <PointedEars@web.de>
Newsgroups	comp.lang.javascript
Subject	Re: test for autoplay
Date	Wed, 21 Jan 2015 23:03:43 +0100
Organization	PointedEars Software (PES)
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Andrew Poulos wrote:

> I found this that looked worth trying
> 
> var AUTOPLAY = false;
> 
> (function() {
>    var mp3 = 'data:audio/mpeg;base64,/[ a data URI here ];
> 
>    try {
>      var audio = new Audio();
>      audio.autoplay = true;
> 
>      $(audio).on('play', function() {
>        AUTOPLAY = true;
>      });
> 
>      audio.src = mp3;
>    } catch(e) {
>      // error
>    }
> })();
> 
> Alas I don't understand "$(audio).on('play', function() {"
> 
> What is it doing?

This is the jQuery way of adding an event listener for the “play” event to 
the element referred to by “audio”.  Apparently the standards-compliant

  audio.onplay = function () {
    AUTOPLAY = true;
  };

was too hard for them :->

This code creates an “audio” element in memory (using a proprietary 
approach; the standards-compliant approach would be 
“document.createElement("audio")”) and sets its “autoplay” property, thereby 
the “autoplay” attribute of the corresponding element, to “true”.  The 
assumption is that if autoplay is supported, the “play” event is fired 
immediately after the “src” property was assigned to, thereby the “src” 
attribute was set, to refer to an MPEG-1/2 Audio Layer Ⅲ (mp3) resource by 
“data:” URI.  In that case, the value of the global “AUTOPLAY” variable 
(both misguided and misplaced) is set to “true”.

This approach may or may not work as it may or may not be based on flawed 
logic.  One issue of several is that a decoder for mp3 may not be installed 
in a browser on a mobile device.

-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | SVN: <http://PointedEars.de/wsvn/>
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Thread

test for autoplay Andrew Poulos <ap_prog@hotmail.com> - 2015-01-22 07:55 +1100
  Re: test for autoplay Scott Sauyet <scott.sauyet@gmail.com> - 2015-01-21 13:17 -0800
    Re: test for autoplay Andrew Poulos <ap_prog@hotmail.com> - 2015-01-22 08:42 +1100
  Re: test for autoplay Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-01-21 23:03 +0100
    Re: test for autoplay "Christoph M. Becker" <cmbecker69@arcor.de> - 2015-01-21 23:35 +0100
      Re: test for autoplay Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-01-22 01:10 +0100
        Re: test for autoplay "Christoph M. Becker" <cmbecker69@arcor.de> - 2015-01-22 14:14 +0100

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