Function encodePayload

packages/engine.io/lib/parser-v3/index.ts:222–245

(packets, supportsBinary, callback)

 */

export function encodePayload (packets, supportsBinary, callback) {
  if (typeof supportsBinary === 'function') {
    callback = supportsBinary;
    supportsBinary = null;
  }

  if (supportsBinary && hasBinary(packets)) {
    return encodePayloadAsBinary(packets, callback);
  }

  if (!packets.length) {
    return callback('0:');
  }

  function encodeOne(packet, doneCallback) {
    encodePacket(packet, supportsBinary, false, function(message) {
      doneCallback(null, setLengthHeader(message));
    });
  }

  map(packets, encodeOne, function(err, results) {
    return callback(results.join(''));
  });
};

function setLengthHeader(message) {
  return message.length + ':' + message;