正则表达式否定接受带有前导零的数字

Question

So below is the directive i am using to ensure the input is purely number from 0-9.

import { Directive, HostListener, ElementRef } from "@angular/core";

@Directive({
  selector: "[numbersOnly]",
})
export class OnlynumberDirective {
  constructor(private _el: ElementRef) {}

  @HostListener("input", ["$event"]) onInputChange(event) {
    const initalValue = this._el.nativeElement.value;

    this._el.nativeElement.value = initalValue.replace(/[^0-9]*/g, "");
    if (initalValue !== this._el.nativeElement.value) {
      event.stopPropagation();
    }
  }
}

At the moment, it only allows numbers (no special characters) as it performs data cleanup and replaces the non-numeric chars with empty space. Now i want to change my regex to not allow numbers containing leading zeros. It can have zeros but not just in the start.

1. 90123 -> Accepted
2. 100001 -> Accepted
3. 01223 -> Not accepted
4. 0 -> Not accepted

Please suggest me a regex that can work with this.

Answer 1

You can use /\D|^0+/g for data cleanup like so:

initalValue.replace(/\D|^0+/g, "");

In English it says:

Find anything not a digit ( \D ) or ( | ) leading zeros ( ^0+ ) and replace it with nothing

 console.log('90123'.replace(/\D|^0+/g, "")); console.log('100001'.replace(/\D|^0+/g, "")); console.log('01223'.replace(/\D|^0+/g, "")); console.log('001223'.replace(/\D|^0+/g, "")); console.log('0'.replace(/\D|^0+/g, ""));

Answer 2

Or you can use

/^[^1-9]+/g

Leading ^ character that is not ^ number 1 to 9

 console.log('00090123'.replace(/^[^1-9]+/g, "")); console.log('100001'.replace(/^[^1-9]+/g, "")); console.log('01223'.replace(/^[^1-9]+/g, "")); console.log('001223'.replace(/^[^1-9]+/g, "")); console.log('0'.replace(/^[^1-9]+/g, ""));

Answer 3

you can try this

 var str="90123 " var str1="100001" var str3="01223" pattern=/^0|D{1}\d+/g console.log(str.replace(pattern,"")) console.log(str1.replace(pattern,"")) console.log(str3.replace(pattern,""))