Angular 4 input only numbers Directive

I was working on a project in Angular 4 and needed to implement input fields that only accept numerical values. My first thought was to simply add the HTML5 type=”number” to the input. Unfortunately, this isn’t supported in Internet Explorer 10 and some of the clients would most likely be using Internet Explorer 10. My only other option was to implement a directive. Thanks to this StackOverflow answer, I was able to modify it to my needs.

Implementing Token Interceptor and Retry in Angular 4

If you are building a web application using Angular 4 or Angular 5 there’s a good chance that you might be working with JWT tokens. Luckily, implementing token interceptor and retry in Angular 4 and beyond is very easy thanks to the new HTTP Interceptors. Using this, we can add an authorization header to every outbound request while also implementing a retry mechanism for requests that fail due to an expired token.

Implementing Token Interceptor and Retry in Angular 4

If you are building a web application using Angular 4 or Angular 5 there’s a good chance that you might be working with JWT tokens. Luckily, implementing token interceptor and retry in Angular 4 and beyond is very easy thanks to the new HTTP Interceptors. Using this, we can add an authorization header to every outbound request while also implementing a retry mechanism for requests that fail due to an expired token.

Subscribe to variable change in Angular 4 Service

If you want to subscribe to variable change in Angular 4 service or Angular 5 service, you can use something called the BehaviorSubject from the rxjs library. A behavior subject is like an observable, except that it must be created with an initial value as it is must always return a value even if the subject hasn’t been updated. A behavior subject will always emit it’s first value as soon as it’s described.