使用ngIf检查字符串是否以某些字符开头 [英] Use ngIf checking if a string starts with certain character

问题描述

是否可以通过使用角度来做到这一点?我尝试了两种方式，但都没有用.

Is it possible to do this by using angular? I have tried both ways and none of them work.

<div class="card-1" [ngStyle]="{'opacity':cardNumber[0] == '4' ? '0.5' : 'none' }"></div>

帮助

 [ngStyle]="{'opacity':cardNumber.startsWith('4') ? '0.5' : 'none' }">

推荐答案

您最好为此创建一个管道:

You might as well create a pipe for that:

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

@Pipe({
  name: 'startsWith'
})
export class StartsWithPipe implements PipeTransform {
  transform(fullText: string, textMatch: string): boolean {
    return fullText.startsWith(textMatch);
  }
}

并像这样使用它:

<div [ngStyle]="{'opacity': ('hello' | startsWith:'he') ? '0.5' : 'none' }">
  Test
</div>

这是一个有效的Stackblitz示例:
https://stackblitz.com/edit/angular-nmjvu3

Here's a working Stackblitz example:
https://stackblitz.com/edit/angular-nmjvu3

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