Method constructor

lib/index.js:1341–1409

(db, opts, callback)

class Changes$1 extends EE {
  constructor(db, opts, callback) {
    super();
    this.db = db;
    opts = opts ? clone(opts) : {};
    var complete = opts.complete = once((err, resp) => {
      if (err) {
        if (listenerCount(this, 'error') > 0) {
          this.emit('error', err);
        }
      } else {
        this.emit('complete', resp);
      }
      this.removeAllListeners();
      db.removeListener('destroyed', onDestroy);
    });
    if (callback) {
      this.on('complete', function (resp) {
        callback(null, resp);
      });
      this.on('error', callback);
    }
    const onDestroy = () => {
      this.cancel();
    };
    db.once('destroyed', onDestroy);

    opts.onChange = (change, pending, lastSeq) => {
      /* istanbul ignore if */
      if (this.isCancelled) {
        return;
      }
      tryCatchInChangeListener(this, change, pending, lastSeq);
    };

    var promise = new Promise(function (fulfill, reject) {
      opts.complete = function (err, res$$1) {
        if (err) {
          reject(err);
        } else {
          fulfill(res$$1);
        }
      };
    });
    this.once('cancel', function () {
      db.removeListener('destroyed', onDestroy);
      opts.complete(null, {status: 'cancelled'});
    });
    this.then = promise.then.bind(promise);
    this['catch'] = promise['catch'].bind(promise);
    this.then(function (result) {
      complete(null, result);
    }, complete);



    if (!db.taskqueue.isReady) {
      db.taskqueue.addTask((failed) => {
        if (failed) {