js readStreamToEnd

async function readStreamToEnd(rstream){
  rstream.resume();
  let prom=new Promise((resolve,reject)=>{
    var buf = Buffer('');
    rstream.on('data', function(newbuf) { buf=Buffer.concat([buf,newbuf]); });
    rstream.on('end', function() { resolve(buf.toString()); });
    rstream.on('error', function(e) { reject(e); });
  });
  return await prom;
}