console.log blocks action when disconnected from WebIDE (or a terminal program)

[espruino-discuss]

Posted at 2018-02-21 by ClearMemory041063

If you use console.log in a program but disconnect the program execution is blocked when the console buffer is full.

For example:

// Console.log blocks LED On/Off flashing when
// disconnected

var l=0;
myinterval=setInterval(function () {
   digitalWrite(LED1,l=!l);
}, 1000);

var i=0;
setInterval(function(){
  console.log(i);
  i++;
},200);

// load program
// LED is pulsing On an dOff
// Console is displaying the count in i
// Disconnect the WebIde
// The LED action stops
// Reconnect the WebIde
// Buffered count is displayed
// LED resumes action

and the output:

          |_| http://espruino.com
 1v95 Copyright 2017 G.Williams
>
=undefined
0
1
2
3
4
5
6
7
8
9
10
11
Disconnected   ( the LED stops until reconnected)
>
12
13
14
15
16

If you are using console.log to show the connection status etc. of a WiFi connection, disconnecting the WebIde will block the server.

Not complaining about this, just posting to let others know about this gotcha.

[gfwilliams]

Posted at 2018-02-21 by @gfwilliams

Wow, I'm amazed you only just hit this :) It's been in troubleshooting for a while (http://www.espruino.com/Troubleshooting) but might be a bit hard to find.

It's because Espruino doesn't want to lose data when it's connected to USB, and it has no way of knowing if data is not being accepted because the computer on the end is busy, or because no application is running on it