How do I restrict an input to only accept numbers?

Question

I am using ngChange in AngularJS to trigger a custom function that will remove any letters the user adds to the input.

Answer 1

Here's my implementation of the $parser solution that @Mark Rajcok recommends as the best method. It's essentially @pkozlowski.opensource's excellent $parser for text answer but rewritten to only allow numerics. All credit goes to him, this is just to save you the 5 minutes of reading that answer and then rewriting your own:

app.directive('numericOnly', function(){
    return {
        require: 'ngModel',
        link: function(scope, element, attrs, modelCtrl) {

            modelCtrl.$parsers.push(function (inputValue) {
                var transformedInput = inputValue ? inputValue.replace(/[^\d.-]/g,'') : null;

                if (transformedInput!=inputValue) {
                    modelCtrl.$setViewValue(transformedInput);
                    modelCtrl.$render();
                }

                return transformedInput;
            });
        }
    };
});

And you'd use it like this:

<input type="text" name="number" ng-model="num_things" numeric-only>

Interestingly, spaces never reach the parser unless surrounded by an alphanumeric, so you'd have to .trim() as needed. Also, this parser does NOT work on <input type="number">. For some reason, non-numerics never make it to the parser where they'd be removed, but they do make it into the input control itself.

Answer 2

<input type="text" ng-model="employee.age" valid-input input-pattern="[^0-9]+" placeholder="Enter an age" />

<script>
var app = angular.module('app', []);

app.controller('dataCtrl', function($scope) {
});

app.directive('validInput', function() {
  return {
    require: '?ngModel',
    scope: {
      "inputPattern": '@'
    },
    link: function(scope, element, attrs, ngModelCtrl) {

      var regexp = null;

      if (scope.inputPattern !== undefined) {
        regexp = new RegExp(scope.inputPattern, "g");
      }

      if(!ngModelCtrl) {
        return;
      }

      ngModelCtrl.$parsers.push(function(val) {
        if (regexp) {
          var clean = val.replace(regexp, '');
          if (val !== clean) {
            ngModelCtrl.$setViewValue(clean);
            ngModelCtrl.$render();
          }
          return clean;
        }
        else {
          return val;
        }

      });

      element.bind('keypress', function(event) {
        if(event.keyCode === 32) {
          event.preventDefault();
        }
      });
    }
}}); </script>

Answer 3

SOLUTION: I make a directive for all inputs, number, text, or any, in the app, so you can input a value and change the event. Make for angular 6

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

 @Directive({
// tslint:disable-next-line:directive-selector
selector: 'input[inputType]'
})
  export class InputTypeDirective {
 constructor(private _el: ElementRef) {}

 @Input() inputType: string;
 // tipos: number, letter, cuit, tel

@HostListener('input', ['$event']) onInputChange(event) {
if (!event.data) {
  return;
}

switch (this.inputType) {
  case 'number': {
    const initalValue = this._el.nativeElement.value;
    this._el.nativeElement.value = initalValue.replace(/[^0-9]*/g, '');
    if (initalValue !== this._el.nativeElement.value) {
      event.stopPropagation();
    }
     break;
          }
       case 'text': {
        const result = event.data.match(/[^a-zA-Z Ññ]*/g);
        if (result[0] !== '') {
           const initalValue = this._el.nativeElement.value;
           this._el.nativeElement.value = initalValue.replace(
          /[^a-zA-Z Ññ]*/g,
           ''
         );
           event.stopPropagation();
        }
        break;
    }
        case 'tel':
          case 'cuit': {
         const initalValue = this._el.nativeElement.value;
      this._el.nativeElement.value = initalValue.replace(/[^0-9-]*/g, '');
       if (initalValue !== this._el.nativeElement.value) {
         event.stopPropagation();
       }
     }
   }
  }
   }

HTML

     <input matInput inputType="number" [formControlName]="field.name" [maxlength]="field.length" [placeholder]="field.label | translate"  type="text" class="filter-input">

Answer 4

None of the solutions proposed worked fine for me, and after a couple of hours I finally found the way.

This is the angular directive:

angular.module('app').directive('restrictTo', function() {
    return {
        restrict: 'A',
        link: function (scope, element, attrs) {
            var re = RegExp(attrs.restrictTo);
            var exclude = /Backspace|Enter|Tab|Delete|Del|ArrowUp|Up|ArrowDown|Down|ArrowLeft|Left|ArrowRight|Right/;

            element[0].addEventListener('keydown', function(event) {
                if (!exclude.test(event.key) && !re.test(event.key)) {
                    event.preventDefault();
                }
            });
        }
    }
});

And the input would look like:

<input type="number" min="0" name="inputName" ng-model="myModel" restrict-to="[0-9]">

The regular expression evaluates the pressed key, not the value.

It also works perfectly with inputs type="number" because prevents from changing its value, so the key is never displayed and it does not mess with the model.

Answer 5

Basic HTML

<input type="number" />

Basic bootstrap

<input class="form-control" type="number" value="42" id="my-id">

Answer 6

Using ng-pattern on the text field:

<input type="text"  ng-model="myText" name="inputName" ng-pattern="onlyNumbers">

Then include this on your controller

$scope.onlyNumbers = /^\d+$/;