Uncaught SyntaxError: BREAK statement outside of SWITCH, FOR or WHILE loop

Give this a shot:

 var oWifi = require('Wifi');
oWifi.scan(function(aAp) {
  aAp.sort(function(a, b) {
    var r = a.rssi === b.rssi ? 0 : (a.rssi < b.rssi ? 1 : -1);
    return r;
  });
  console.log(aAp);
  var i=0, k, foundMy;
  while (!foundMy && i<aAp.length) {
    k = 0; // <---- restart k IN outer loop... only once outside is not enough
    while (!foundMy && k<aMyAp.length) {
      if (aAp[i].ssid === aMyAp[k].ssid) { // <---- compare [i] w/ [k]
        foundMy = aMyAp[k];                //          ...and not [i] w/ [i] 
      }
      k++;
    }
    i++;
  }
  if (foundMy) {
    oWifi.connect(foundMy.ssid, {password: foundMy.pwd}, function(err) {
      if (err===null) {
         console.log('Connection success to:', foundMy.ssid);
      }
    });
  } else {
    console.log('no Ap found');
  }
});

...there were obviously also some other issues... - see // <---- comments - were there?

What is the sort helping with? ...do you have duplicate ssid in scan result and want only the one to match w/ highest rssi value?

(Since labels are bad in general and worst in compiler free environment - as Espruino - in regard of nested control management, labels are not implemented in Espruino. Why though the simple, one-level break is not working... I don't know).