angular - 比较和更改日期格式，如今天、昨天、

Question

我有以下数据:

     {
       "content": [
       {
         "id": 15076772,
         "date": "2019-06-26T15:37:36"
       },
       {
        "id": 15074042,
        "date": "2019-03-05T15:06:57"
       },
       {
        "id": 15073812,
        "date": "2019-09-17T14:32:18"
       },
       {
        "id": 15073810,
        "date": "2019-09-18T14:31:56"
       }
     ]
   }

我想根据当天的日期将每个日期转换为特定格式

如果 newDate() = 2019-09-18T14: 31: 56 我们将在今天发布如果 newDate() 不等于当天的日期而是昨天的日期，则显示昨天

然后在星期几之后根据日期和一周后离开数据的正常日期。有点像聊天系统中显示的日期

不知道angular能不能自动完成

不知道angular能不能自动做到，我知道Moment.js可以用日历时间做到。

如果有人能教我，那就太好了。

Answer 1

Angular 没有内置此功能，但您可以构建自己的管道或使用现有的管道 (https://github.com/AndrewPoyntz/time-ago-pipe)

不是我开发的，但是一个很好的例子:

https://github.com/AndrewPoyntz/time-ago-pipe/blob/master/time-ago.pipe.ts

如果您不介意它不会随着时间的流逝而更新，您可以让它变得纯粹并只针对您的情况(今天、昨天等)保持简单。

@Pipe({
    name:'timeAgo',
    pure:false
})
export class TimeAgoPipe implements PipeTransform, OnDestroy {
    private timer: number;
    constructor(private changeDetectorRef: ChangeDetectorRef, private ngZone: NgZone) {}
    transform(value:string) {
        this.removeTimer();
        let d = new Date(value);
        let now = new Date();
        let seconds = Math.round(Math.abs((now.getTime() - d.getTime())/1000));
        let timeToUpdate = (Number.isNaN(seconds)) ? 1000 : this.getSecondsUntilUpdate(seconds) *1000;
        this.timer = this.ngZone.runOutsideAngular(() => {
            if (typeof window !== 'undefined') {
                return window.setTimeout(() => {
                    this.ngZone.run(() => this.changeDetectorRef.markForCheck());
                }, timeToUpdate);
            }
            return null;
        });
        let minutes = Math.round(Math.abs(seconds / 60));
        let hours = Math.round(Math.abs(minutes / 60));
        let days = Math.round(Math.abs(hours / 24));
        let months = Math.round(Math.abs(days/30.416));
        let years = Math.round(Math.abs(days/365));
        if (Number.isNaN(seconds)){
            return '';
        } else if (seconds <= 45) {
            return 'a few seconds ago';
        } else if (seconds <= 90) {
            return 'a minute ago';
        } else if (minutes <= 45) {
            return minutes + ' minutes ago';
        } else if (minutes <= 90) {
            return 'an hour ago';
        } else if (hours <= 22) {
            return hours + ' hours ago';
        } else if (hours <= 36) {
            return 'a day ago';
        } else if (days <= 25) {
            return days + ' days ago';
        } else if (days <= 45) {
            return 'a month ago';
        } else if (days <= 345) {
            return months + ' months ago';
        } else if (days <= 545) {
            return 'a year ago';
        } else { // (days > 545)
            return years + ' years ago';
        }
    }
    ngOnDestroy(): void {
        this.removeTimer();
    }
    private removeTimer() {
        if (this.timer) {
            window.clearTimeout(this.timer);
            this.timer = null;
        }
    }
    private getSecondsUntilUpdate(seconds:number) {
        let min = 60;
        let hr = min * 60;
        let day = hr * 24;
        if (seconds < min) { // less than 1 min, update every 2 secs
            return 2;
        } else if (seconds < hr) { // less than an hour, update every 30 secs
            return 30;
        } else if (seconds < day) { // less then a day, update every 5 mins
            return 300;
        } else { // update every hour
            return 3600;
        }
    }
}