Flashing lights example try 4 not working

[espruino-discuss]

Posted at 2014-01-22 by nglod

Hello,

I just received my espruinos and started typing a few examples.
I have upgraded the firmware as explained in the quick start guide and I am following this tutorial: http://www.espruino.com/Flashing+Lights
The code under "try 4" is not working as expected:

Pin.prototype.startFlashing = function(period) { 
  var on = false;
  setInterval(function() {
    on = !on;
    digitalWrite(this, on);
  }, period);
}
LED1.startFlashing(100);

On the console I can read "ERROR: Invalid pin!". There seems to be a problem handling "this", in fact the issue seems to be the same as in this other forum post: http://forum.espruino.com/conversations/389/

The code works fine with the following modification:

Pin.prototype.startFlashing = function(period) {
  var me = this;
  var on = false;
  setInterval(function() {
    on = !on;
    digitalWrite(me, on);
  }, period);
}

LED1.startFlashing(100);

Just letting you know, I don't know this should be considered a bug in the code or in the documentation.

Thanks a lot!

[gfwilliams]

Posted at 2014-01-23 by @gfwilliams

Great, thanks for letting me know! I've just updated the code/documentation.

It's because Espruino used to remember the value of 'this' when setInterval was called (which I believe was wrong). I fixed that and forgot to change the docs :)