simple javascript evaluator service (to test larger MTU)

desay-jseval.js

maxlen=56;
NRF.setServices({
  0x190A : { // Desay AT commands service ID (DS-D6, HX03W)
    0x0002 : {
      maxLen: maxlen,
      notify: true
    },
    0x0001 : {
      writable : true,
      maxLen: maxlen,
      onWrite : function(evt) {
        handleWrite(evt,'0x190A','0x0002',maxlen);
      }
    }
  }
},{uart:true}); // still enable console

function handleWrite(evt, svc, ch, len){
  //log(svc+" got "+evt.data);
  var val=handleCommand(E.toString(evt.data));
  if (val===undefined || val===null) return;
  if (typeof(val)==="number") val=val.toString();
  if (typeof(val)==="object") val=JSON.stringify(val);
  if (typeof(val)==="string") {
    //log("reply="+val);
    val=E.toArrayBuffer(val);
  }
  if (!val.length) return;
  // now update service with the value
  var c={};
  var s={};s[svc]=c;
  c[ch]={value : val, notify: true};
  if (val.length<=len)
    NRF.updateServices(s);
  else {
    // if longer than maxlen split into chunks
    var l=val.length;
    var i=0;
    while (l>0){
      c[ch].value=new Uint8Array(val,i,(l>len)?len:l);
      NRF.updateServices(s);
      i+=len;l-=len;
    }
  }
}
var line="";

function handleCommand(s){
  line+=s;
  if (s.endsWith("\n") || s.endsWith("\r")){
    var res=handleLine(line.trim());//trim removes crlf
    line="";
    return res;
  }
}

function handleLine(l){
  try {
    res=eval(l);
  } catch(e){
    res="Uncaught "+e.type+": "+e.message;
  }
  return res;
}