Allow Only Numbers to Be Typed in a Textbox

Allow only numbers to be typed in a textbox

You could subscribe for the onkeypress event:

<input type="text" class="textfield" value="" id="extra7" name="extra7" onkeypress="return isNumber(event)" />

and then define the isNumber function:

function isNumber(evt) {
    evt = (evt) ? evt : window.event;
    var charCode = (evt.which) ? evt.which : evt.keyCode;
    if (charCode > 31 && (charCode < 48 || charCode > 57)) {
        return false;
    }
    return true;
}

You can see it in action here.

HTML text input allow only numeric input

JavaScript

You can filter the input values of a text <input> with the following setInputFilter function (supports Copy+Paste, Drag+Drop, keyboard shortcuts, context menu operations, non-typeable keys, the caret position, different keyboard layouts, validity error message, and all browsers since IE 9):

// Restricts input for the given textbox to the given inputFilter function.
function setInputFilter(textbox, inputFilter, errMsg) {
  [ "input", "keydown", "keyup", "mousedown", "mouseup", "select", "contextmenu", "drop", "focusout" ].forEach(function(event) {
    textbox.addEventListener(event, function(e) {
      if (inputFilter(this.value)) {
        // Accepted value.
        if ([ "keydown", "mousedown", "focusout" ].indexOf(e.type) >= 0){
          this.classList.remove("input-error");
          this.setCustomValidity("");
        }

        this.oldValue = this.value;
        this.oldSelectionStart = this.selectionStart;
        this.oldSelectionEnd = this.selectionEnd;
      }
      else if (this.hasOwnProperty("oldValue")) {
        // Rejected value: restore the previous one.
        this.classList.add("input-error");
        this.setCustomValidity(errMsg);
        this.reportValidity();
        this.value = this.oldValue;
        this.setSelectionRange(this.oldSelectionStart, this.oldSelectionEnd);
      }
      else {
        // Rejected value: nothing to restore.
        this.value = "";
      }
    });
  });
}

You can now use the setInputFilter function to install an input filter:

setInputFilter(document.getElementById("myTextBox"), function(value) {
  return /^\d*\.?\d*$/.test(value); // Allow digits and '.' only, using a RegExp.
}, "Only digits and '.' are allowed");

Apply your preferred style to the input-error class. Here’s a suggestion:

.input-error{
  outline: 1px solid red;
}

Note that you still must do server side validation!

Another caveat is that this will break the undo stack since it sets this.value directly.
This means that CtrlZ will not work to undo inputs after typing an invalid character.

Demo

See the JSFiddle demo for more input filter examples or run the Stack snippet below:

// Restricts input for the given textbox to the given inputFilter.
function setInputFilter(textbox, inputFilter, errMsg) {
  [ "input", "keydown", "keyup", "mousedown", "mouseup", "select", "contextmenu", "drop", "focusout" ].forEach(function(event) {
    textbox.addEventListener(event, function(e) {
      if (inputFilter(this.value)) {
        // Accepted value.
        if ([ "keydown", "mousedown", "focusout" ].indexOf(e.type) >= 0) {
          this.classList.remove("input-error");
          this.setCustomValidity("");
        }
        
        this.oldValue = this.value;
        this.oldSelectionStart = this.selectionStart;
        this.oldSelectionEnd = this.selectionEnd;
      }
      else if (this.hasOwnProperty("oldValue")) {
        // Rejected value: restore the previous one.
        this.classList.add("input-error");
        this.setCustomValidity(errMsg);
        this.reportValidity();
        this.value = this.oldValue;
        this.setSelectionRange(this.oldSelectionStart, this.oldSelectionEnd);
      }
      else {
        // Rejected value: nothing to restore.
        this.value = "";
      }
    });
  });
}

// Install input filters.
setInputFilter(document.getElementById("intTextBox"), function(value) {
  return /^-?\d*$/.test(value);
}, "Must be an integer");
setInputFilter(document.getElementById("uintTextBox"), function(value) {
  return /^\d*$/.test(value);
}, "Must be an unsigned integer");
setInputFilter(document.getElementById("intLimitTextBox"), function(value) {
  return /^\d*$/.test(value) && (value === "" || parseInt(value) <= 500);
}, "Must be between 0 and 500");
setInputFilter(document.getElementById("floatTextBox"), function(value) {
  return /^-?\d*[.,]?\d*$/.test(value);
}, "Must be a floating (real) number");
setInputFilter(document.getElementById("currencyTextBox"), function(value) {
  return /^-?\d*[.,]?\d{0,2}$/.test(value);
}, "Must be a currency value");
setInputFilter(document.getElementById("latinTextBox"), function(value) {
  return /^[a-z]*$/i.test(value);
}, "Must use alphabetic latin characters");
setInputFilter(document.getElementById("hexTextBox"), function(value) {
  return /^[0-9a-f]*$/i.test(value);
}, "Must use hexadecimal characters");

.input-error {
  outline: 1px solid red;
}

<h2>JavaScript input filter showcase</h2>
<p>Supports Copy+Paste, Drag+Drop, keyboard shortcuts, context menu operations, non-typeable keys, the caret position, different keyboard layouts, and <a href="https://caniuse.com/#feat=input-event" target="_blank">all browsers since IE 9</a>.</p>
<p>There is also a <a href="https://jsfiddle.net/emkey08/tvx5e7q3" target="_blank">jQuery version</a> of this.</p>
<table>
  <tr>
    <td>Integer</td>
    <td><input id="intTextBox"></td>
  </tr>
  <tr>
    <td>Integer >= 0</td>
    <td><input id="uintTextBox"></td>
  </tr>
  <tr>
    <td>Integer >= 0 and <= 500</td>
    <td><input id="intLimitTextBox"></td>
  </tr>
  <tr>
    <td>Float (use . or , as decimal separator)</td>
    <td><input id="floatTextBox"></td>
  </tr>
  <tr>
    <td>Currency (at most two decimal places)</td>
    <td><input id="currencyTextBox"></td>
  </tr>
  <tr>
    <td>A-Z only</td>
    <td><input id="latinTextBox"></td>
  </tr>
  <tr>
    <td>Hexadecimal</td>
    <td><input id="hexTextBox"></td>
  </tr>
</table>

Allow only numbers into a input text box

You can achieve this by pure JavaScript. Create this function that you can reuse in your script.

function allowNumbersOnly(e) {
    var code = (e.which) ? e.which : e.keyCode;
    if (code > 31 && (code < 48 || code > 57)) {
        e.preventDefault();
    }
}

You may preferably call this onkeypress event handler.

<input type="text" id="onlyNumbers" onkeypress="allowNumbersOnly(event)" />

function allowNumbersOnly(e) {    var code = (e.which) ? e.which : e.keyCode;    if (code > 31 && (code < 48 || code > 57)) {        e.preventDefault();    }}

<!DOCTYPE html><html><head>  <meta charset="utf-8">  <title>JS Bin</title></head><body>    Try editing in me:    <input type="text" id="onlyNumbers" onkeypress="allowNumbersOnly(event)" /></body></html>

How do I make a textbox that only accepts numbers?

Two options:

1. Use a NumericUpDown instead. NumericUpDown does the filtering for you, which is nice. Of course it also gives your users the ability to hit the up and down arrows on the keyboard to increment and decrement the current value.

2. Handle the appropriate keyboard events to prevent anything but numeric input. I've had success with this two event handlers on a standard TextBox:

   private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
   {
       if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar) &&
           (e.KeyChar != '.'))
       {
               e.Handled = true;
       }
   
       // only allow one decimal point
       if ((e.KeyChar == '.') && ((sender as TextBox).Text.IndexOf('.') > -1))
       {
           e.Handled = true;
       }
   }
   

You can remove the check for '.' (and the subsequent check for more than one '.') if your TextBox shouldn't allow decimal places. You could also add a check for '-' if your TextBox should allow negative values.

If you want to limit the user for number of digit, use: textBox1.MaxLength = 2; // this will allow the user to enter only 2 digits

HTML text input allow only numeric input

JavaScript

You can filter the input values of a text <input> with the following setInputFilter function (supports Copy+Paste, Drag+Drop, keyboard shortcuts, context menu operations, non-typeable keys, the caret position, different keyboard layouts, validity error message, and all browsers since IE 9):

// Restricts input for the given textbox to the given inputFilter function.
function setInputFilter(textbox, inputFilter, errMsg) {
  [ "input", "keydown", "keyup", "mousedown", "mouseup", "select", "contextmenu", "drop", "focusout" ].forEach(function(event) {
    textbox.addEventListener(event, function(e) {
      if (inputFilter(this.value)) {
        // Accepted value.
        if ([ "keydown", "mousedown", "focusout" ].indexOf(e.type) >= 0){
          this.classList.remove("input-error");
          this.setCustomValidity("");
        }

        this.oldValue = this.value;
        this.oldSelectionStart = this.selectionStart;
        this.oldSelectionEnd = this.selectionEnd;
      }
      else if (this.hasOwnProperty("oldValue")) {
        // Rejected value: restore the previous one.
        this.classList.add("input-error");
        this.setCustomValidity(errMsg);
        this.reportValidity();
        this.value = this.oldValue;
        this.setSelectionRange(this.oldSelectionStart, this.oldSelectionEnd);
      }
      else {
        // Rejected value: nothing to restore.
        this.value = "";
      }
    });
  });
}

You can now use the setInputFilter function to install an input filter:

setInputFilter(document.getElementById("myTextBox"), function(value) {
  return /^\d*\.?\d*$/.test(value); // Allow digits and '.' only, using a RegExp.
}, "Only digits and '.' are allowed");

Apply your preferred style to the input-error class. Here’s a suggestion:

.input-error{
  outline: 1px solid red;
}

Note that you still must do server side validation!

Another caveat is that this will break the undo stack since it sets this.value directly.
This means that CtrlZ will not work to undo inputs after typing an invalid character.

Demo

See the JSFiddle demo for more input filter examples or run the Stack snippet below:

// Restricts input for the given textbox to the given inputFilter.
function setInputFilter(textbox, inputFilter, errMsg) {
  [ "input", "keydown", "keyup", "mousedown", "mouseup", "select", "contextmenu", "drop", "focusout" ].forEach(function(event) {
    textbox.addEventListener(event, function(e) {
      if (inputFilter(this.value)) {
        // Accepted value.
        if ([ "keydown", "mousedown", "focusout" ].indexOf(e.type) >= 0) {
          this.classList.remove("input-error");
          this.setCustomValidity("");
        }
        
        this.oldValue = this.value;
        this.oldSelectionStart = this.selectionStart;
        this.oldSelectionEnd = this.selectionEnd;
      }
      else if (this.hasOwnProperty("oldValue")) {
        // Rejected value: restore the previous one.
        this.classList.add("input-error");
        this.setCustomValidity(errMsg);
        this.reportValidity();
        this.value = this.oldValue;
        this.setSelectionRange(this.oldSelectionStart, this.oldSelectionEnd);
      }
      else {
        // Rejected value: nothing to restore.
        this.value = "";
      }
    });
  });
}

// Install input filters.
setInputFilter(document.getElementById("intTextBox"), function(value) {
  return /^-?\d*$/.test(value);
}, "Must be an integer");
setInputFilter(document.getElementById("uintTextBox"), function(value) {
  return /^\d*$/.test(value);
}, "Must be an unsigned integer");
setInputFilter(document.getElementById("intLimitTextBox"), function(value) {
  return /^\d*$/.test(value) && (value === "" || parseInt(value) <= 500);
}, "Must be between 0 and 500");
setInputFilter(document.getElementById("floatTextBox"), function(value) {
  return /^-?\d*[.,]?\d*$/.test(value);
}, "Must be a floating (real) number");
setInputFilter(document.getElementById("currencyTextBox"), function(value) {
  return /^-?\d*[.,]?\d{0,2}$/.test(value);
}, "Must be a currency value");
setInputFilter(document.getElementById("latinTextBox"), function(value) {
  return /^[a-z]*$/i.test(value);
}, "Must use alphabetic latin characters");
setInputFilter(document.getElementById("hexTextBox"), function(value) {
  return /^[0-9a-f]*$/i.test(value);
}, "Must use hexadecimal characters");

.input-error {
  outline: 1px solid red;
}

<h2>JavaScript input filter showcase</h2>
<p>Supports Copy+Paste, Drag+Drop, keyboard shortcuts, context menu operations, non-typeable keys, the caret position, different keyboard layouts, and <a href="https://caniuse.com/#feat=input-event" target="_blank">all browsers since IE 9</a>.</p>
<p>There is also a <a href="https://jsfiddle.net/emkey08/tvx5e7q3" target="_blank">jQuery version</a> of this.</p>
<table>
  <tr>
    <td>Integer</td>
    <td><input id="intTextBox"></td>
  </tr>
  <tr>
    <td>Integer >= 0</td>
    <td><input id="uintTextBox"></td>
  </tr>
  <tr>
    <td>Integer >= 0 and <= 500</td>
    <td><input id="intLimitTextBox"></td>
  </tr>
  <tr>
    <td>Float (use . or , as decimal separator)</td>
    <td><input id="floatTextBox"></td>
  </tr>
  <tr>
    <td>Currency (at most two decimal places)</td>
    <td><input id="currencyTextBox"></td>
  </tr>
  <tr>
    <td>A-Z only</td>
    <td><input id="latinTextBox"></td>
  </tr>
  <tr>
    <td>Hexadecimal</td>
    <td><input id="hexTextBox"></td>
  </tr>
</table>

How to allow only numeric (0-9) in HTML inputbox using jQuery?

^{Note: This is an updated answer. Comments below refer to an old version which messed around with keycodes.}

jQuery

Try it yourself on JSFiddle.

There is no native jQuery implementation for this, but you can filter the input values of a text <input> with the following inputFilter plugin (supports Copy+Paste, Drag+Drop, keyboard shortcuts, context menu operations, non-typeable keys, the caret position, different keyboard layouts, validity error message, and all browsers since IE 9):

// Restricts input for the set of matched elements to the given inputFilter function.
(function($) {
  $.fn.inputFilter = function(callback, errMsg) {
    return this.on("input keydown keyup mousedown mouseup select contextmenu drop focusout", function(e) {
      if (callback(this.value)) {
        // Accepted value
        if (["keydown","mousedown","focusout"].indexOf(e.type) >= 0){
          $(this).removeClass("input-error");
          this.setCustomValidity("");
        }
        this.oldValue = this.value;
        this.oldSelectionStart = this.selectionStart;
        this.oldSelectionEnd = this.selectionEnd;
      } else if (this.hasOwnProperty("oldValue")) {
        // Rejected value - restore the previous one
        $(this).addClass("input-error");
        this.setCustomValidity(errMsg);
        this.reportValidity();
        this.value = this.oldValue;
        this.setSelectionRange(this.oldSelectionStart, this.oldSelectionEnd);
      } else {
        // Rejected value - nothing to restore
        this.value = "";
      }
    });
  };
}(jQuery));

You can now use the inputFilter plugin to install an input filter:

$(document).ready(function() {
  $("#myTextBox").inputFilter(function(value) {
    return /^\d*$/.test(value);    // Allow digits only, using a RegExp
  },"Only digits allowed");
});

Apply your preferred style to input-error class. Here's a suggestion:

.input-error{
  outline: 1px solid red;
}

See the JSFiddle demo for more input filter examples. Also note that you still must do server side validation!

Pure JavaScript (without jQuery)

jQuery isn't actually needed for this, you can do the same thing with pure JavaScript as well. See this answer.

HTML 5

HTML 5 has a native solution with <input type="number"> (see the specification), but note that browser support varies:

• Most browsers will only validate the input when submitting the form, and not when typing.
• Most mobile browsers don't support the step, min and max attributes.
• Chrome (version 71.0.3578.98) still allows the user to enter the characters e and E into the field. Also see this question.
• Firefox (version 64.0) and Edge (EdgeHTML version 17.17134) still allow the user to enter any text into the field.

Try it yourself on w3schools.com.

How to make HTML input tag only accept numerical values?

HTML 5

You can use HTML5 input type number to restrict only number entries:

<input type="number" name="someid" />

This will work only in HTML5 complaint browser. Make sure your html document's doctype is:

<!DOCTYPE html>

See also https://github.com/jonstipe/number-polyfill for transparent support in older browsers.

JavaScript

Update: There is a new and very simple solution for this:

It allows you to use any kind of input filter on a text <input>,
including various numeric filters. This will correctly handle
Copy+Paste, Drag+Drop, keyboard shortcuts, context menu operations,
non-typeable keys, and all keyboard layouts.

See this answer or try it yourself on JSFiddle.

For general purpose, you can have JS validation as below:

function isNumberKey(evt){
    var charCode = (evt.which) ? evt.which : evt.keyCode
    if (charCode > 31 && (charCode < 48 || charCode > 57))
        return false;
    return true;
}

<input name="someid" type="number" onkeypress="return isNumberKey(event)"/>

If you want to allow decimals replace the "if condition" with this:

if (charCode > 31 && (charCode != 46 &&(charCode < 48 || charCode > 57)))

Source: HTML text input allow only numeric input

JSFiddle demo: http://jsfiddle.net/viralpatel/nSjy7/

How to allow only numbers in textbox in reactjs?

Basic idea is:

Use controlled component (use value and onChange property of input field), and inside onChange handle check whether the entered value is proper number or not. Update the state only when entered value is a valid number.

For that use this regex: /^[0-9\b]+$/;

onChange handler will be:

onChange(e){
    const re = /^[0-9\b]+$/;

    // if value is not blank, then test the regex

    if (e.target.value === '' || re.test(e.target.value)) {
       this.setState({value: e.target.value})
    }
}

Working example:

class App extends React.Component{   constructor(){      super();      this.state = {value: ''};      this.onChange = this.onChange.bind(this)   }      onChange(e){      const re = /^[0-9\b]+$/;      if (e.target.value === '' || re.test(e.target.value)) {         this.setState({value: e.target.value})      }   }      render(){     return <input value={this.state.value} onChange={this.onChange}/>   }}
ReactDOM.render(<App/>,document.getElementById('app'))

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script><script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<div id='app'/>

allow only numbers in input text box

You need:

• read about regular expressions
• create a regexp that accepts only numbers /^\d+$/
• in event handler test input value by the regexp regexp.test(value)

const input = document.getElementById('input')const onlyNumbersRegExp = /^\d+$/;
input.addEventListener('input', function() {  if (onlyNumbersRegExp.test(input.value)) {    console.log('only numbers');  } else {    console.log('not only numbers');  }})

<input id="input" type="text" placeholder="enter only number" />

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