javascript only numbers

only_numbers.html

<h2>jQuery input filter showcase</h2>
<p><b>Supports:</b> Copy+Paste, Drag+Drop, keyboard shortcuts, context menu operations, non-typeable keys, and all keyboard layouts.</p>
<p><b>Compatibility:</b> Cross-browser and on mobile, IE 9+.</p>
<p><b>Note:</b> There is also a <a href="https://jsfiddle.net/emkey08/zgvtjc51" target="_blank">pure JavaScript version</a> of this, jQuery isn't actually needed.</p>
<table>
  <tr><td>Integer:</td><td><input id="intTextBox"></td></tr>
  <tr><td>Integer up to 1500:</td><td><input id="intLimitTextBox"></td></tr>
  <tr><td>Unsigned integer:</td><td><input id="uintTextBox"></td></tr>
  <tr><td>Hex integer:</td><td><input id="hexTextBox"></td></tr>
  <tr><td>Float:</td><td><input id="floatTextBox"></td></tr>
  <tr><td>Currency (two decimals):</td><td><input id="currencyTextBox"></td></tr>
</table>

<script>
// FUENTE
// https://stackoverflow.com/questions/469357/html-text-input-allows-only-numeric-input
// https://jsfiddle.net/emkey08/tvx5e7q3
// Restricts input for each element in the set of matched elements to the given inputFilter.
(function($) {
  $.fn.inputFilter = function(inputFilter) {
    return this.on("input keydown keyup mousedown mouseup select contextmenu drop", function() {
      if (inputFilter(this.value)) {
        this.oldValue = this.value;
        this.oldSelectionStart = this.selectionStart;
        this.oldSelectionEnd = this.selectionEnd;
      } else if (this.hasOwnProperty("oldValue")) {
        this.value = this.oldValue;
        this.setSelectionRange(this.oldSelectionStart, this.oldSelectionEnd);
      }
    });
  };
}(jQuery));


// Install input filters.
$("#intTextBox").inputFilter(function(value) {
  return /^-?\d*$/.test(value); });
$("#intLimitTextBox").inputFilter(function(value) {
  return /^\d*$/.test(value) && (value === "" || parseInt(value) <= 1500); });
$("#uintTextBox").inputFilter(function(value) {
  return /^\d*$/.test(value); });
$("#hexTextBox").inputFilter(function(value) {
  return /^[0-9a-f]*$/i.test(value); });
$("#floatTextBox").inputFilter(function(value) {
  return /^-?\d*[.,]?\d*$/.test(value); });
$("#currencyTextBox").inputFilter(function(value) {
  return /^-?\d*[.,]?\d{0,2}$/.test(value); });
</script>