Proper way to restrict text input values e g only numbers

Question

Is it possible to implement an input that allows to type only numbers inside without manual handling of event target value   In React  it is possible to define value property and afterwards input change will be basically bound to the value  not possible to modify it without value change   See example  And it works just fine without any efforts   In Angular 2 it is possible to define  value   but it will just set the value initially  and afterwards input is not prevented from the modifications   I was playing around with ngModel and  value     input   see example   But in both implementation there is essential problem    when you type 10  model value is 10  input value is 10  - correct when you type 10d afterwards  model value is 10 - not modified  all non-digits has been removed  input value is 10d  - incorrect  because the model value is the same as before when you type 10d3 -  model value is 103  input value is 103  - correct   How to do that simple  from the first glance  component  without manually handling event target value      UPDATE I am not looking for native HTML5 input number  element here  Numbers input here is just for the example - there could be way more tasks when i need to restrict input text    Moreover  input number  is 1  not restricting me from typing 10ddd and 2   less important  contains arrows that i do not need   And the problem here is to prevent user from typing something beyond the restricted values  instead of allow to input anything and validate it afterwards

User · Answer

I think a custom ControlValueAccessor is the best option   Not tested but as far as I remember  this should work    lt input   ngModel    value  pattern   0-9   gt

User · Answer

Tested Answer By me   form html   lt input type  text   keypress   restrictNumeric  event   gt    form component ts   public restrictNumeric e      let input    if  e metaKey    e ctrlKey        return true        if  e which     32       return false        if  e which     0       return true        if  e which  lt  33        return true        input   String fromCharCode e which     return      d s   test input

User · Answer

I use this one    import   Directive  ElementRef  HostListener  Input  Output  EventEmitter   from   angular core     Directive       selector    ngModel  onlyNumber        host              input     onInputChange  event            export class OnlyNumberDirective         Input   onlyNumber  boolean       Output   ngModelChange  EventEmitter lt any gt    new EventEmitter        constructor public el  ElementRef               public onInputChange  event           if   event target value     -                 return                     if   event target value  amp  amp   event target value endsWith                     return                      event target value   this parseNumber  event target value            event target dispatchEvent new Event  input                 HostListener  blur      event        public onBlur event  Event            if   this onlyNumber                return                     this el nativeElement value   this parseNumber this el nativeElement value           this el nativeElement dispatchEvent new Event  input                private parseNumber input  any   any           let trimmed   input replace    0-9  -   g               let parsedNumber   parseFloat trimmed            return  isNaN parsedNumber    parsedNumber                  and usage is following    lt input onlyNumbers  true        gt

User · Answer

Anoher one   lt form  formGroup   myForm  novalidate gt       lt input type  text  class  form-control  id  data  name  data             formControlName  input3   item  input   change item value   gt   lt  form gt    myForm value  json    change value string          let lastchar   value substr value length - 1       if    new RegExp   0-9    test lastchar                value value substr 0 value length-1         this myForm controls  input3   setValue value                if you use from driven template     lt input type  text  class  form-control  id  data  name  data           ngModel    data   item  input   change item   gt       data    change item any          let value item value      let lastchar   value substr value length - 1       if    new RegExp   0-9    test lastchar                value value substr 0 value length-1         item value this data value              Update As  BikashBishwokarma comment  this not work if you insert a character in middle  We can change the function by some like    change item any          let value item value      let pos item selectionStart      if    new RegExp    0-9      test value                item value this data value replace    0-9   g             item selectionStart   item selectionEnd   pos-1              See  how mainten the cursor position

User · Answer

After did lot of research finally I create a function which full fill the requirement  The function which I created restrict all special character and allow only alphabets and number   and that function works fine for both either you did copy paste and typing both  Hope it works      public inputValidator event  any          console log event target value       const pattern      a-zA-Z0-9               let inputChar   String fromCharCode event charCode      if   pattern test event target value           event target value   event target value replace    a-zA-Z0-9  g                invalid character  prevent input                   lt input type  text    ngModel    abc abc   input   inputValidator  event     gt    How you use -  1  Add above method in your class component of ts file  2  Call method inputValidator  event  on input event

User · Answer

I think this will solve your problem  I created one directive which filters input from the user and restricts number or text which you want   This solution is for up to Ionic-3 and Angular-4 users   import   Directive  HostListener  Input   from   angular core   import   Platform   from  ionic-angular           Generated class for the AlphabateInputDirective directive        See https   angular io api core Directive for more info on Angular    Directives       Directive     selector    keyboard-input-handler      Attribute selector    export class IonicKeyboardInputHandler       Input  type   inputType  string     isNumeric  boolean   true    str  string         arr  any            constructor      public platForm  Platform           console log  Hello IonicKeyboardInputHandler Directive             HostListener  keyup      event    onInputStart e            this str   e target value            this arr   this str split           this isNumeric   this inputType     number    true   false        if e target value split      length     2         return false                 if this isNumeric         e target value   parseInt this arr filter  c   gt  isFinite c   join                       else       e target value   this arr filter  c   gt   isFinite c   join                   return true

User · Answer

lt input type  number  onkeypress  return event charCode  gt   48  amp  amp  event charCode  lt   57  ondragstart  return false   ondrop  return false   gt        Input filed only accept numbers  But it s temporary fix only

User · Answer

In html     lt input  keypress   onlyNumber event    gt    In Component   onlyNumber evt        evt    evt    evt   window event      var charCode    evt which    evt which   evt keyCode      if  charCode  gt  31  amp  amp   charCode  lt  48    charCode  gt  57             return false            return true

User · Answer

The inputmask plugin does the best job of this  Its extremely flexible in that you can supply whatever regex you like to restrict input  It also does not require JQuery   Step 1  Install the plugin   npm install --save inputmask   Step2  create a directive to wrap the input mask   import  Directive  ElementRef  Input  from   angular core   import   as Inputmask from  inputmask      Directive     selector    app-restrict-input       export class RestrictInputDirective         map of some of the regex strings I m using  TODO  add your own    private regexMap         integer     0-9          float      -    0-9        0-9          words     A-z    s         point25     -  0-9        25    50    75             constructor private el  ElementRef         Input  app-restrict-input     public set defineInputType type  string        Inputmask  regex  this regexMap type   placeholder              mask this el nativeElement            Step 3    lt input type  text  app-restrict-input  integer  gt    Check out their github docs for more information

User · Answer

Below is working solution using NgModel  Add variable    public Phone string    In html add         lt input class  input-width    ngModel    Phone   keyup   keyUpEvent  event          type  text  class  form-control  placeholder  Enter Mobile Number  gt    In Ts file      keyUpEvent event  any        const pattern     0-9   -            let inputChar   String fromCharCode event keyCode        if   pattern test inputChar              invalid character  prevent input       if this Phone length gt 0                  this Phone  this Phone substr 0 this Phone length-1

User · Answer

A few of the answers did not work for me so I took the best bits from some of the answers  thanks guys  and created an Angular 5 Directive that should do the job  and more  for you  It maybe not perfect but it offers flexibility   import   Directive  HostListener  ElementRef  Input  Renderer2   from   angular core     Directive   selector    appInputMask      export class InputMaskDirective    Input  appInputMask   inputType  string   showMsg   false  pattern  RegExp   private regexMap        add your own integer     0-9     g  float      -    0-9        0-9    g  words     A-z    s   g  point25     -  0-9        25    50    75    g  badBoys                 -     g     constructor public el  ElementRef  public renderer  Renderer2         HostListener  keypress      event    onInput e    this pattern   this regexMap this inputType  const inputChar   e key  this pattern lastIndex   0     dont know why but had to add this  if  this pattern test inputChar           success   this renderer setStyle this el nativeElement   color    green       this badBoyAlert  black      else      this badBoyAlert  black         do something her to indicate invalid character   this renderer setStyle this el nativeElement   color    red      e preventDefault              badBoyAlert color  string        setTimeout      gt          this showMsg   true        this renderer setStyle this el nativeElement   color   color          2000             HTML       lt input class  form-control  appInputMask  badBoys  gt

User · Answer

To catch all the event surrounding model changes   can consider using   lt input  ngModelChange   inputFilter  event    gt    It will detect copy   paste  keyup  any condition that changes the value of the model   And then   inputFilter event  any        const pattern     0-9   -          let inputChar   String fromCharCode event charCode        if   pattern test inputChar              invalid character  prevent input       event preventDefault

User · Answer

In component ts add this function   keyUp event  any        const pattern     0-9   -          let inputChar   String fromCharCode event key        if   pattern test inputChar              invalid character  prevent input       event preventDefault              In your template use the following   lt input keyup    keyUp  event   gt    This will catch the input before angular2 catches the event

User · Answer

In HTML in  lt input gt  field write   keypress   onlyNumberKey  event    and in ts file write   onlyNumberKey event        return  event charCode    8    event charCode    0    null   event charCode  gt   48  amp  amp  event charCode  lt   57

User · Answer

You can use the HTML5 input of type number  It does not accept any characters in its declaration   lt input type  number    model    myvar  min 0 max 100 step 5   gt    Here is an example of its usage with angular 2   model    http   www webpackbin com VJNUNF0M-

[angular] Proper way to restrict text input values (e.g. only numbers)

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