Recursive Function Hanging

...it is always the same issue: Active executing code in level 0 messes with the upload completion detection from editor as well as console, and in your case it is even worse: your console.log() goes directly after that upload process. Reason: the (default, regular) console connection is used to upload... and because arriving code is executed as soon as it is a complete JavaScript statement or expression. The upload uses a timeout to check for a 'completion prompt' from Espruino. It does not get it but rather gets stuff from your application.

Put your function invocation code into a function (which you call within) onInit() function. This has other advantages: you will be able to save() your code in flash (enter save() in the console after upload), and the code will run on power on.

PS: without the convenience of last code line (setTimeout(onInit,...), you have to start your code every time after upload by entering onInit(); in the console... Helpful read up on these subjects is the conversation about simple explanation how to save code that espruino run on start?.

var temp = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0];
var send = function(times, i) {
  console.log('foobar', i);
  if (i < times.length) {
    send(times, i + 1);
  }
};

function onInit() {
  send(temp, 1);
}

setTimeout(onInit, 1000); // DEVELOPMENT CONVENIENCE - REMOVE BEFORE SAVING