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

you may also want to remove the 0 at the beginning of the input... I simply add an if block to Mordred answer above because I cannot make a comment yet...

  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();
              }
              //clear beginning 0
              if(transformedInput == 0){
                modelCtrl.$setViewValue(null);
                modelCtrl.$render();
              }
              return transformedInput;
          });
      }
    };
  })

Answer 2

I know this is old, but I've created a directive for this purpose in case anyone is looking for an easy solution. Very simple to use.

You can check it out here.

Answer 3

I ended up creating a modified directive of the above code to accept input and change the format on the fly...

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

           element.bind('keyup', function (inputValue, e) {
             var strinput = modelCtrl.$$rawModelValue;
             //filter user input
             var transformedInput = strinput ? strinput.replace(/[^,\d.-]/g,'') : null;
             //remove trailing 0
             if(transformedInput.charAt(0) <= '0'){
               transformedInput = null;
               modelCtrl.$setViewValue(transformedInput);
               modelCtrl.$render();
             }else{
               var decimalSplit = transformedInput.split(".")
               var intPart = decimalSplit[0];
               var decPart = decimalSplit[1];
               //remove previously formated number
               intPart = intPart.replace(/,/g, "");
               //split whole number into array of 3 digits
               if(intPart.length > 3){
                 var intDiv = Math.floor(intPart.length / 3);
                 var strfraction = [];
                 var i = intDiv,
                     j = 3;

                 while(intDiv > 0){
                   strfraction[intDiv] = intPart.slice(intPart.length-j,intPart.length - (j - 3));
                   j=j+3;
                   intDiv--;
                 }
                 var k = j-3;
                 if((intPart.length-k) > 0){
                   strfraction[0] = intPart.slice(0,intPart.length-k);
                 }
               }
               //join arrays
               if(strfraction == undefined){ return;}
                 var currencyformat = strfraction.join(',');
                 //check for leading comma
                 if(currencyformat.charAt(0)==','){
                   currencyformat = currencyformat.slice(1);
                 }

                 if(decPart ==  undefined){
                   modelCtrl.$setViewValue(currencyformat);
                   modelCtrl.$render();
                   return;
                 }else{
                   currencyformat = currencyformat + "." + decPart.slice(0,2);
                   modelCtrl.$setViewValue(currencyformat);
                   modelCtrl.$render();
                 }
             }
            });
      }
  };

})

Answer 4

All the above solutions are quite large, i wanted to give my 2 cents on this.

I am only checking if the value inputed is a number or not, and checking if it's not blank, that's all.

Here is the html:

<input type="text" ng-keypress="CheckNumber()"/>

Here is the JS:

$scope.CheckKey = function () {
    if (isNaN(event.key) || event.key === ' ' || event.key === '') {
        event.returnValue = '';
    }
};

It's quite simple.

I belive this wont work on Paste tho, just so it's known.

For Paste, i think you would need to use the onChange event and parse the whole string, quite another beast the tamme. This is specific for typing.

UPDATE for Paste: just add this JS function:

$scope.CheckPaste = function () {
    var paste = event.clipboardData.getData('text');

    if (isNaN(paste)) {
        event.preventDefault();
        return false;
    }
};

And the html input add the trigger:

<input type="text" ng-paste="CheckPaste()"/>

I hope this helps o/

Answer 5

Here is a Plunker handling any situation above proposition do not handle.
By using $formatters and $parsers pipeline and avoiding type="number"

And here is the explanation of problems/solutions (also available in the Plunker) :

/*
 *
 * Limit input text for floating numbers.
 * It does not display characters and can limit the Float value to X numbers of integers and X numbers of decimals.
 * min and max attributes can be added. They can be Integers as well as Floating values.
 *
 * value needed    |    directive
 * ------------------------------------
 * 55              |    max-integer="2"
 * 55.55           |    max-integer="4" decimal="2" (decimals are substracted from total length. Same logic as database NUMBER type)
 *
 *
 * Input type="number" (HTML5)
 *
 * Browser compatibility for input type="number" :
 * Chrome : - if first letter is a String : allows everything
 *          - if first letter is a Integer : allows [0-9] and "." and "e" (exponential)
 * Firefox : allows everything
 * Internet Explorer : allows everything
 *
 * Why you should not use input type="number" :
 * When using input type="number" the $parser pipeline of ngModel controller won't be able to access NaN values.
 * For example : viewValue = '1e'  -> $parsers parameter value = "".
 * This is because undefined values are not allowes by default (which can be changed, but better not do it)
 * This makes it impossible to modify the view and model value; to get the view value, pop last character, apply to the view and return to the model.
 *
 * About the ngModel controller pipelines :
 * view value -> $parsers -> model value
 * model value -> $formatters -> view value
 *
 * About the $parsers pipeline :
 * It is an array of functions executed in ascending order.
 * When used with input type="number" :
 * This array has 2 default functions, one of them transforms the datatype of the value from String to Number.
 * To be able to change the value easier (substring), it is better to have access to a String rather than a Number.
 * To access a String, the custom function added to the $parsers pipeline should be unshifted rather than pushed.
 * Unshift gives the closest access to the view.
 *
 * About the $formatters pipeline :
 * It is executed in descending order
 * When used with input type="number"
 * Default function transforms the value datatype from Number to String.
 * To access a String, push to this pipeline. (push brings the function closest to the view value)
 *
 * The flow :
 * When changing ngModel where the directive stands : (In this case only the view has to be changed. $parsers returns the changed model)
 *     -When the value do not has to be modified :
 *     $parsers -> $render();
 *     -When the value has to be modified :
 *     $parsers(view value) --(does view needs to be changed?) -> $render();
 *       |                                  |
 *       |                     $setViewValue(changedViewValue)
 *       |                                  |
 *       --<-------<---------<--------<------
 *
 * When changing ngModel where the directive does not stand :
 *     - When the value does not has to be modified :
 *       -$formatters(model value)-->-- view value
 *     -When the value has to be changed
 *       -$formatters(model vale)-->--(does the value has to be modified) -- (when loop $parsers loop is finished, return modified value)-->view value
 *                                              |
 *                                  $setViewValue(notChangedValue) giving back the non changed value allows the $parsers handle the 'bad' value
 *                                               |                  and avoids it to think the value did not changed
 *                Changed the model <----(the above $parsers loop occurs)
 *
 */