handling of this strange(?)

Just to add, if you do:

function test(){  
  var interval;
  console.log(this);
  this.a = 0;
  interval = setInterval(function(){
      this.a++;console.log(this,this.a);
    },2000);
}
var b = new test();

and compare, it looks like this is handled fine. The issue is that undefined+1 (and hence this.a++) returns NaN in other JS implementations, but in Espruino it just returns 1. I'll make a bug for that, and also for a++ errors so at least we can track it.

bugs:

https://github.com/espruino/Espruino/iss­ues/146
https://github.com/espruino/Espruino/iss­ues/147