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https://github.com/Tinkoff/ng-event-plugins

This is an Angular library for optimizing performance sensitive events and declarative preventDefault, stopPropagation and capture phase listeners.
https://github.com/Tinkoff/ng-event-plugins

angular angular-library capture events optimization preventdefault stoppropagation trigger-change-detection

Last synced: 2 months ago
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This is an Angular library for optimizing performance sensitive events and declarative preventDefault, stopPropagation and capture phase listeners.

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# Angular Event Plugins



[![npm version](https://img.shields.io/npm/v/@tinkoff/ng-event-plugins.svg)](https://npmjs.com/package/@tinkoff/ng-event-plugins)

[![npm bundle size](https://img.shields.io/bundlephobia/minzip/@tinkoff/ng-event-plugins)](https://bundlephobia.com/result?p=@tinkoff/ng-event-plugins)

[![Coverage Status](https://coveralls.io/repos/github/TinkoffCreditSystems/ng-event-plugins/badge.svg?branch=master)](https://coveralls.io/github/TinkoffCreditSystems/ng-event-plugins?branch=master)

[![angular-open-source-starter](https://img.shields.io/badge/made%20with-angular--open--source--starter-d81676?logo=angular)](https://github.com/TinkoffCreditSystems/angular-open-source-starter)

[![telegram chat](https://img.shields.io/badge/support-Contact%20us-blue)](https://t.me/taiga_ui)



**@tinkoff/ng-event-plugins** is a tiny (1KB gzip) library for optimizing change detection cycles for performance

sensitive events (such as _touchmove_, _scroll_, _drag_ etc.) and declarative _preventDefault()_ and

_stopPropagation()_.



## How to use



1. Add `EventPluginsModule` to your app module:



   ```typescript

   import {NgModule} from '@angular/core';

   import {BrowserModule} from '@angular/platform-browser';

   import {EventPluginsModule} from '@tinkoff/ng-event-plugins'; // <-- THIS



   @NgModule({

     bootstrap: [

       /*...*/

     ],

     imports: [

       /*...*/

       BrowserModule,

       EventPluginsModule, // <-- GOES HERE

     ],

     declarations: [

       /*...*/

     ],

   })

   export class AppModule {}

   ```



> `BrowserModule` or `BrowserAnimationsModule` must go first. You will see a warning if you mess the order.



2. Use new modifiers for events in templates and in `@HostListener`:



   - `.stop` to call stopPropagation() on event

   - `.prevent` to call preventDefault() on event

   - `.self` to skip bubbled events

   - `.silent` to call event handler outside Angular's `NgZone`

   - `.capture` to listen to events in

     [capture phase](https://developer.mozilla.org/en-US/docs/Web/API/Event/eventPhase)

   - `.passive` to add

     [passive event listener](https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener#improving_scrolling_performance_with_passive_listeners)

   - `.once` to remove event listener after first callback



   For example:



   ```html

   
Clicking on this DIV will not move focus


   ```



   ```html

   
Clicks on this DIV will not bubble up


   ```



   ```html

   
Callbacks to mousemove will not trigger change detection


   ```



   ```html

   


     
Clicks will be stopped before reaching this DIV


   


   ```



3. You can also re-enter `NgZone` and trigger change detection, using `@shouldCall` decorator that takes a predicate

   function as argument:



```html



  Scrolling this DIV will only trigger change detection and onScroll callback if it is scrolled to bottom



```



```typescript

import {shouldCall} from '@tinkoff/ng-event-plugins';



export function scrollFilter({

 scrollTop, scrollHeight, clientHeight

}: HTMLElement): boolean {

    return scrollTop === scrollHeight - clientHeight;

}



// ...



@shouldCall(scrollFilter)

onScroll(_element: HTMLElement): void {

    this.someService.requestMoreData();

}

```



> All examples above work the same when used with `@HostListener` and `CustomEvent`



### Important notes



- Predicate is called with the same arguments as the decorated method and in the context of class instance (has access

  to `this`)



- Decorated method will be called and change detection triggered if predicate returns `true`.



- Predicates must be exported named function for AOT, arrow functions will trigger build error.



- `.silent` modifier will not work with built-in keyboard pseudo-events, such as `keydown.enter` or `keydown.arrowDown`

  since Angular re-enters `NgZone` inside internal handlers.



## Observable host bindings



In this library there's also a plugin that enables observable host bindings. Sounds weird to do host binding with event

plugin, but the code is actually pretty simple. You can read more about it in

[this article](https://indepth.dev/posts/1429/making-hostbinding-work-with-observables).



To use it you need to couple `@HostListener` and `@HostBinding` on the same `Observable` property with following syntax:



```ts

@HostBinding('$.disabled')

@HostListener('$.disabled')

readonly disabled$ = asCallable(this.service.loading$)

```



This supports all the native Angular syntax, such as `class.class-name` or `style.width.px`.



**IMPORTANT NOTES:**



- Until [this issue](https://github.com/angular/angular/issues/12045) is resolved you would have to use

  `NO_ERRORS_SCHEMA` in your module in order to bind to arbitrary properties

- `asCallable` is a utility function from this library that simply adds `Function` to the type so Angular thinks it

  could be a host listener

- To bind attributes you need to add `.attr` modifier in the end, not the beginning like in basic Angular binding. This

  is due to Angular using regexp to match for `attr.` string in `@HostBinding` decorator:



```ts

@HostBinding('$.aria-label.attr')

@HostListener('$.aria-label.attr')

readonly label$ = asCallable(this.translations.get$('label'));

```



## Demo



You can try this

[interactive demo](https://codesandbox.io/s/github/TinkoffCreditSystems/ng-event-plugins/tree/master/projects/demo)



You can also read this [detailed article](https://indepth.dev/supercharge-event-management-in-your-angular-application/)

explaining how this library works



## Maintained



**@tinkoff/ng-event-plugins** is a part of [Taiga UI](https://github.com/Tinkoff/taiga-ui) libraries family which is backed and used by a

large enterprise. This means you can rely on timely support and continuous development.



## License



🆓 Feel free to use our library in your commercial and private applications



All **@tinkoff/ng-event-plugins** packages are covered by [Apache 2.0](/LICENSE)



Read more about this license [here](https://choosealicense.com/licenses/apache-2.0/)



## Open-source



Do you also want to open-source something, but hate the collateral work? Check out this

[Angular Open-source Library Starter](https://github.com/TinkoffCreditSystems/angular-open-source-starter) we’ve created

for our projects. It got you covered on continuous integration, pre-commit checks, linting, versioning + changelog, code

coverage and all that jazz.