Resolving Async Validation

Because validate returns synchronously, your application must recognize when async validation needs to be resolved. The validation result returned from validate will only include the validateAsync property when a async validation needs to be resolved. If the validateAsync result property exists, it will be a function that returns a Promise.

const result = validate(usernameIsAvailable, 'marty');

// The application defines a `handleValidationResult` function
// to handle validation results when the are completed

if (result.validateAsync) {
    result.validateAsync().then((asyncResult) => handleValidationResult(asyncResult));
} else {
    handleValidationResult(result);
}

Async Validation Helper: validateAsync

To avoid boilerplate code, Strickland provides a validateAsync function as a named export. This function always returns a Promise, regardless of whether validation completed synchronously or needs to be resolved asynchronously.

import {validateAsync} from 'strickland';

const result = validateAsync(usernameIsAvailable, 'marty');
result.then((asyncResult) => handleValidationResult(asyncResult));