Delayed hover event in Angular

Use case: Display tooltip only after user has been hovering for some time already. If he leaves sooner, then do not display anything. Technologies Angular, RxJs, Ngx UntilDestroy Authors David Votrubec and Luďek Cakl Implementation The logic behind is that we combine two streams. One stream is for the mouseenter event, and the other is […]

Ctrl-click directive in Angular

Angular has lot of built-in directives for listening for events like click, dblclick, mousein, mouseout etc. But sometimes you need something more sophisticated, like detect ctrl-click. I did not find any directive which would suit my needs, so I had to write my own. Be aware that normal browser behaviour for ctrl-click is to open […]

File validators in Angular

Whenever you allow users to upload files to your server, you should have both client side and server side validation. Most likely you will validate file size and file type, identifiable by the file extension. FileValidator covers all three aspects. Example of usage is below the source code. If you are using Angular, you can […]

Angular (click) not fired and how to fix it

Sometimes, very rarely, you can run into situation then Angular does not fire the (click) event. Or it fires later, on the 2nd click. It can be really hard to debug and figure out what causes it. So here are my two cents. This can be caused by view being updated while user clicks. What […]

Decimal number is not a number!

You have an input field, where user can enter decimal values. Problem is, that some cultures use decimal point “.” and some uses decimal comma “,”. So what is a valid number in one culture, is not a number at all in a different culture. You can see the full list of differences on wikipedia. There is no built-in […]

Invoke native element method with Angular 6

The useful method invokeElementMethod() has been removed from the new Renderer v3 in the upcoming version 6 of Angular. What does it mean? For example it is now harder to invoke focus() on input field or create custom native event, which bubbles up. The motivation of the Angular team is that this method has not been […]

Workaround for ExpressionChangedAfterItHasBeenCheckedError in async pipe

Imagine that you have this piece of code, where userInfo$ is Observable and it value is not yet emitted. <app-change-email [currentEmail]=”(userInfo$ | async).user.email”></app-change-email> The code works, but it will report error ExpressionChangedAfterItHasBeenCheckedError to the console (only in dev mode). That is because the component has received the value, but the value has changed later. Angular […]

Angular custom event bubbling

Custom events in Angular by default do not bubble up. It is because they are not really events, they are based on EventEmitter, which is similar to pub/sub mechanism. You can read lengthy discussion about it on Angular’s Github. Unfortunately the examples provided by Angular team often mention $event as named parameter in the event listener, […]