如何检查字符串的第一个字符是否是数字作为 *ngIf 中的条件

Question

I am trying to check if a document name it is coming with the first char as a number. I am not able to make my code go in and display "Dummy string". I tried with this two options but it is not working.

1.
let documentPDF = "6487954.pdf"
<ng-container *ngIf="Character.isDigit(ParseInt(documentPDF.charAt(0))) == false">
         Dummy string
</ng-container>

2.
let document = "6487954.pdf"
<ng-container *ngIf="isNaN(ParseInt(documentPDF.charAt(0))) == false">
         Dummy string
</ng-container>

Thank you for your help.

Answer 1

you can use a regular expression:

try this:

let documentPDF = "6487954.pdf"

<ng-container *ngIf="!/^\d/.test(documentPDF)">
  Dummy string
</ng-container>