ionic-coginito-signup-function.cognito-service.ts

  signUp(email, password) {
    return new Promise((resolved, reject) => {
      const userPool = new AWSCognito.CognitoUserPool(this._POOL_DATA);

      let userAttribute = [];
      userAttribute.push(
        new AWSCognito.CognitoUserAttribute({ Name: "email", Value: email })
      );

      userPool.signUp(email, password, userAttribute, null, function(err, result) {
        if (err) {
          reject(err);
        } else {
          resolved(result);
        }
      });
    });
  }