Angular 5 - Only Number Input, Only Number Decimal

only-number.directive.md

Angular 5,6,7,8,9 - Only Number Input, Only Decimal Input

v1 Online Demo: https://codesandbox.io/s/v1-angular-numeric-ljwlb

v1 Gist : https://gist.github.com/ahmeti/5ca97ec41f6a48ef699ee6606560d1f7/e36956cc355ad1bad6898e9eede5d7a9219947e8

v2 Online Demo: https://codesandbox.io/s/v2-angular-numeric-3w2wr

Allow Only Numbers (Without Decimal)

<input numeric type="text">

Allow Numbers & Only Two Decimals [0-9] (With Decimal Limit)

<input numeric decimals="2" type="text">

// Version 2

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

@Directive({
    selector: "[numeric]"
})
export class NumericDirective {
    @Input("decimals") decimals: int = 0;

    private check(value: string) {
        if (this.decimals <= 0) {
            return String(value).match(new RegExp(/^\d+$/));
        } else {
            var regExpString =
                "^\\s*((\\d+(\\.\\d{0," +
                this.decimals +
                "})?)|((\\d*(\\.\\d{1," +
                this.decimals +
                "}))))\\s*$";
            return String(value).match(new RegExp(regExpString));
        }
    }

    private run(oldValue) {
        setTimeout(() => {
            let currentValue: string = this.el.nativeElement.value;
            if (currentValue !== '' && !this.check(currentValue)) {
                this.el.nativeElement.value = oldValue;
            }
        });
    }

    constructor(private el: ElementRef) {}

    @HostListener("keydown", ["$event"])
    onKeyDown(event: KeyboardEvent) {
        this.run(this.el.nativeElement.value);
    }

    @HostListener("paste", ["$event"])
    onPaste(event: ClipboardEvent) {
        this.run(this.el.nativeElement.value);
    }

}

To access ngControl, add @Optional() @Self() private ngControl: NgControl, to constructor:

 constructor(
    @Optional() @Self() private ngControl: NgControl,
    private el: ElementRef<HTMLInputElement | HTMLTextAreaElement>,
  ) { }

    if (this.ngControl) {
      this.ngControl.control.patchValue(oldValue, { emitEvent: false, onlySelf: true });
    }

Thank you, very useful!
As @rbrijesh mentioned, if one types more than the maximum decimals, the input does not show it, but the value of the input is longer by one number. Is there a fix for this? I could not find what causes it.

Here is a fixed version. It uses NgControl.valueChanges insted of @HostListeners which fixes the extra character at the end of the input when submitting the form.

`

import { Directive, Input, OnInit } from '@angular/core';
import { NgControl } from '@angular/forms';
import { distinctUntilChanged, pairwise, Subscription } from 'rxjs';

@Directive({
    selector: '[restrictedDecimals]'
})
export class InstrumentDecimalsDirective implements OnInit {
    @Input() decimals = 0;
    @Input() negative = 0;
    @Input() separator = ',';
    valueSubscription: Subscription;

    constructor(public ngControl: NgControl) {}

    ngOnInit(): void {
        this.ngControl.valueChanges.pipe(distinctUntilChanged(), pairwise()).subscribe(([oldValue, newValue]) => {
            this.runCheck(oldValue, newValue);
        });
    }

    private runCheck(oldValue, newValue) {
        const allowNegative = this.negative > 0 ? true : false;

        if (allowNegative) {
            if (!['', '-'].includes(newValue) && !this.checkAllowNegative(newValue)) {
                this.ngControl.control.setValue(oldValue);
            }
        } else {
            if (newValue !== '' && !this.check(newValue)) {
                this.ngControl.control.setValue(oldValue);
            }
        }
    }

    private checkAllowNegative(value: string) {
        if (this.decimals <= 0) {
            return new RegExp(/^-?\d+$/).exec(String(value));
        } else {
            const regExpString =
                '^-?\\s*((\\d+(\\' + this.separator + '\\d{0,' + this.decimals + '})?)|((\\d*(\\' + this.separator + '\\d{1,' + this.decimals + '}))))\\s*$';
            return new RegExp(regExpString).exec(String(value));
        }
    }

    private check(value: string) {
        if (this.decimals <= 0) {
            return new RegExp(/^\d+$/).exec(String(value));
        } else {
            const regExpString =
                '^\\s*((\\d+(\\' + this.separator + '\\d{0,' + this.decimals + '})?)|((\\d*(\\' + this.separator + '\\d{1,' + this.decimals + '}))))\\s*$';
            return new RegExp(regExpString).exec(String(value));
        }
    }
}

`

is there any new update for 13

is there any new update for 13

it works with angular v14