Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Use async pipe #227

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Use async pipe #227

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
40 changes: 18 additions & 22 deletions recipes/smartcounter.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -66,45 +66,46 @@ appropriate transition.
#### Angular Version

(
[StackBlitz](https://stackblitz.com/edit/angular-gcnqlq?file=app%2Fnumber-tracker.component.ts)
[StackBlitz](https://stackblitz.com/edit/angular-27anmw?embed=1&file=app/number-tracker.component.ts)
)

```js
import { Component, Input, OnDestroy } from '@angular/core';
import { Component, Input, ChangeDetectionStrategy } from '@angular/core';
import { Subject } from 'rxjs/Subject';
import { timer } from 'rxjs/observable/timer';
import { switchMap, startWith, scan, takeWhile, takeUntil, mapTo } from 'rxjs/operators';
import { of } from 'rxjs/observable/of';
import { Observable } from 'rxjs';
import { switchMap, startWith, scan, takeWhile, mapTo, withLatestFrom } from 'rxjs/operators';

@Component({
selector: 'number-tracker',
template: `
<h3> {{ currentNumber }}</h3>
`
<h3> {{ (currentNumber$ | async) || 0 }}</h3>
`,
changeDetection: ChangeDetectionStrategy.OnPush
})
export class NumberTrackerComponent implements OnDestroy {
export class NumberTrackerComponent {
@Input()
set end(endRange: number) {
this._counterSub$.next(endRange);
}
@Input() countInterval = 20;
public currentNumber = 0;
public currentNumber$ = of(0);
private _counterSub$ = new Subject();
private _onDestroy$ = new Subject();

constructor() {
this._counterSub$
this.currentNumber$ = this._counterSub$
.pipe(
switchMap(endRange => {
withLatestFrom(this.currentNumber$),
switchMap(([endRange, currentNumber]) => {
return timer(0, this.countInterval).pipe(
mapTo(this.positiveOrNegative(endRange, this.currentNumber)),
startWith(this.currentNumber),
mapTo(this.positiveOrNegative(endRange, currentNumber)),
startWith(currentNumber),
scan((acc: number, curr: number) => acc + curr),
takeWhile(this.isApproachingRange(endRange, this.currentNumber))
takeWhile(this.isApproachingRange(endRange, currentNumber))
)
}),
takeUntil(this._onDestroy$)
)
.subscribe((val: number) => this.currentNumber = val);
})
);
}

private positiveOrNegative(endRange, currentNumber) {
Expand All @@ -116,11 +117,6 @@ export class NumberTrackerComponent implements OnDestroy {
? val => val <= endRange
: val => val >= endRange;
}

ngOnDestroy() {
this._onDestroy$.next();
this._onDestroy$.complete();
}
}
```

Expand Down