Best way to restrict a text field to numbers only?

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I\'m using the following Javascript to restrict a text field on my website to only accept numerical input, and no other letters or characters. The problem is, it REALLY reje

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悲哀的现实

2020-12-04 22:27

This is a variation on Robert's answer that allows a single decimal point to be entered. If a decimal point has already been entered, only numbers are accepted as input.

JSFiddle - decimal number input

// Allow only decimal number input

$('#decimalInput').keypress(function (e) {
    var a = [];
    var k = e.which;

    for (i = 48; i < 58; i++)
    a.push(i);

    // allow a max of 1 decimal point to be entered
    if (this.value.indexOf(".") === -1) {
        a.push(46);
    }

    if (!(a.indexOf(k) >= 0)) e.preventDefault();

    $('span').text('KeyCode: ' + k);
});

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走了就别回头了

2020-12-04 22:29

I know that there are already many answers but for the sake of simplicity i would like to add another answer which is simple and self explanatory in which we do not have to remember keycodes and it also works across all browsers.

document.getElementById('myinput').onkeydown = function(e)
 {
     console.log(e.key);
     //console.log(e.target.value);
     switch (e.key)
     {
         case "1":
         case "2":
         case "3":
         case "4":
         case "5":
         case "6":
         case "7":
         case "8":
         case "9":
         case "0":
         case "Backspace":
             return true;
             break;

         case ".":
             if (e.target.value.indexOf(".") == -1)
             {
                 return true;
             }
             else
             {
                 return false;
             }
             break;

         default:
             return false;
     }

 }

<input type="text" placeholder="Enter Value" id="myinput" />

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梦毁少年i

2020-12-04 22:29

This JavaScript function will be used to restrict alphabets and special characters in Textbox , only numbers, delete, arrow keys and backspace will be allowed. JavaScript Code Snippet - Allow Numbers in TextBox, Restrict Alphabets and Special Characters

Tested in IE & Chrome.

JavaScript function

<script type="text/javascript">
    /*code: 48-57 Numbers
      8  - Backspace,
      35 - home key, 36 - End key
      37-40: Arrow keys, 46 - Delete key*/
    function restrictAlphabets(e){
        var x=e.which||e.keycode;
        if((x>=48 && x<=57) || x==8 ||
            (x>=35 && x<=40)|| x==46)
            return true;
        else
            return false;
    }
</script>

HTML Source Code with JavaScript

<html>
    <head>
        <title>JavaScript - Allow only numbers in TextBox (Restrict Alphabets and Special Characters).</title>
        <script type="text/javascript">
            /*code: 48-57 Numbers
              8  - Backspace,
              35 - home key, 36 - End key
              37-40: Arrow keys, 46 - Delete key*/
            function restrictAlphabets(e){
                var x=e.which||e.keycode;
                if((x>=48 && x<=57) || x==8 ||
                    (x>=35 && x<=40)|| x==46)
                    return true;
                else
                    return false;
            }
        </script>
    </head>
<body style="text-align: center;">
    <h1>JavaScript - Allow only numbers in TextBox (Restrict Alphabets and Special Characters).</h1>
    <big>Enter numbers only: </big>
    <input type="text" onkeypress='return restrictAlphabets(event)'/>
</body>

</html>

Refrence

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闹比i

2020-12-04 22:29
Javascript is often used on the browser client side to perform simple tasks that would otherwise require a full postback to the server. Many of those simple tasks involve processing text or characters entered into a form element on a web page, and it is often necessary to know the javascript keycode associated with a character. Here is a reference.

Press a key in the text box below to see the corresponding Javascript key code.
```
        function restrictCharacters(evt) {

            evt = (evt) ? evt : window.event;
            var charCode = (evt.which) ? evt.which : evt.keyCode;
            if (((charCode >= '48') && (charCode <= '57')) || (charCode == '44')) {
                return true;
            }
            else {
                return false;
            }
        }
```
```
Enter Text:
<input type="text" id="number" onkeypress="return restrictCharacters(event);" />
```
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南笙

2020-12-04 22:32

http://jsfiddle.net/PgHFp/

<html>
<head>
<title>Test</title>
<script language="javascript">
function checkInput(ob) {
  var invalidChars = /[^0-9]/gi
  if(invalidChars.test(ob.value)) {
            ob.value = ob.value.replace(invalidChars,"");
      }
}
</script>
</head>

<body>
    <input type="text" onkeyup="checkInput(this)"/>
</body>
</html>

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暖寄归人

2020-12-04 22:34

There is my current solution of numeric input, need to test in different browsers but seems to work

Support comma and period delimiter (czech native is comma), space and numpad/keyboard numbers input. Allow Ctrl+C Ctrl+A or Ctrl+X, arrow navigation and delete block Ctrl+V. React on escape key by blurring input.

Watch my Coffee script:

(($) ->
  $.fn.onlyNumbers = ->
    @each ->
      $(@).keydown (e) ->
        # get code of key
        code = if e.keyCode then e.keyCode else e.which

        return $(@).blur() if code is 27 # blur on escape
        return if code in [46, 8, 9, 13] # 46, 8, 9, 27, 13 = backspace, delete, tab, escape, and enter
        return if (e.ctrlKey or e.metaKey) and code in [65, 67, 88] # ctrl|command + [a, c, x]
        return if code in [96..105] # numpad numbers
        return if code in [48..57] # numbers on keyboard
        return if code in [35..39] # 35..39 - home, end, left, right
        return if code in [188, 190, 32] # comma, period, space
        return if code in [44] # comma, period,

        e.returnValue = false # IE hate you
        e.preventDefault();

      $(@).keypress (e) ->
        code = if e.keyCode then e.keyCode else e.which
        return if code in [44, 46, 32] # comma, period, space
        return if code in [48..57] # numbers on keyboard
        e.returnValue = false # IE hate you
        e.preventDefault();

) jQuery

You can get compiled Javascript here http://goo.gl/SbyhXN

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