Angular 2 日期管周数

Question

我查找了如何在 Angular 2 中返回周数。我还没有找到这个问题的答案。我确实在https://docs.angularjs.org/api/ng/filter/date上找到了在 Angular 1 中，它会是这样的: {{today | date:'w'}} 但这似乎在 Angular 2 中不起作用。我知道我可以编写一个函数来处理这个问题，但这似乎不实用。我是否遗漏了有关 Angular 2 的文档中的某些内容，或者该文档尚未实现？

Answer 1

正如 Günter 所说，编写自己的代码非常简单。

创建一个新的 typescript 文件，week.pipe.ts

import { Pipe, PipeTransform } from '@angular/core';

@Pipe({ name: 'week' })
export class WeekPipe implements PipeTransform {
    transform(value: Date): number {
        return this.getWeekNumber(value);
    }

    // source: http://stackoverflow.com/questions/6117814/get-week-of-year-in-javascript-like-in-php
    private getWeekNumber(d: Date): number {
        // Copy date so don't modify original
        d = new Date(+d);
        d.setHours(0, 0, 0);
        // Set to nearest Thursday: current date + 4 - current day number
        // Make Sunday's day number 7
        d.setDate(d.getDate() + 4 - (d.getDay() || 7));
        // Get first day of year
        var yearStart = new Date(d.getFullYear(), 0, 1);
        // Calculate full weeks to nearest Thursday
        var weekNo = Math.ceil((((d.valueOf() - yearStart.valueOf()) / 86400000) + 1) / 7);
        // Return array of year and week number
        return weekNo;
    }
}

如果您使用 moment，代码会更简单

import { Pipe, PipeTransform } from '@angular/core';
import * as moment from 'moment';

@Pipe({ name: 'week' })
export class WeekPipe implements PipeTransform {
    transform(value: Date): number {
        return moment(value).week();
    }
}

将管道包含在您的 app.module 中

import { NgModule } from '@angular/core';
import { WeekPipe } from './pipes/week.pipe';
@NgModule({
    imports: [
        // your imports
    ],
    declarations: [
        AppComponent,
        WeekPipe      // including the pipe in declarations
    ],
    bootstrap: [AppComponent]
})
export class AppModule { }

然后您可以像往常一样在 HTML 中使用它

<div class="week-number">
    {{ yourDate | week }}
</div>

其中 yourDate 是组件中的 public yourDate: Date = new Date();。