Ionic 4 Async Validation example
Example of Ionic 4 Async Validation using a Reactive Form - updated
Angular Async Validation is a useful technique for validating data against a JSON server, however it can be tricky to set up in Ionic 4 because not all the published examples that work in Angular also work in Ionic 4.
This is an example application created in Ionic 4 that uses Async Validation against a JSON server, in a Reactive Form.
The technique used builds upon examples provided by ...
Fabio Biondi - Angular Reactive Forms Custom Async Validators
Tomasz Sochacki - How to do asynchronous validation in Angular 7
Apart from an installation of Ionic 4, there are no special requirements to run the example, since it uses a publicly accessible JSON API...
JSON Placeholder Typicode
To run the example, use ...
npm i
ionic serve