JQuery allow only two numbers after decimal point

Question

I found the following JQuery function here which prevents a user from entering anything that\'s not a number or a single decimal. The function works well but I\'d like to i

Answer 1

I've updated the function for a few extra cases.

1. It will allow negative numbers
2. It will allow you to edit the left of the decimal when there are already 2 digits to the right
3. It allows you to use the arrow keys and backspace when you are in Firefox
4. It also handles pasted data

/**
 * Given an input field, this function will only allow numbers with up to two decimal places to be input.
 * @param {object} element
 * @return {number}
 */
function forceNumber(element) {
  element
    .data("oldValue", '')
    .bind("paste", function(e) {
      var validNumber = /^[-]?\d+(\.\d{1,2})?$/;
      element.data('oldValue', element.val())
      setTimeout(function() {
        if (!validNumber.test(element.val()))
          element.val(element.data('oldValue'));
      }, 0);
    });
  element
    .keypress(function(event) {
      var text = $(this).val();
      if ((event.which != 46 || text.indexOf('.') != -1) && //if the keypress is not a . or there is already a decimal point
        ((event.which < 48 || event.which > 57) && //and you try to enter something that isn't a number
          (event.which != 45 || (element[0].selectionStart != 0 || text.indexOf('-') != -1)) && //and the keypress is not a -, or the cursor is not at the beginning, or there is already a -
          (event.which != 0 && event.which != 8))) { //and the keypress is not a backspace or arrow key (in FF)
        event.preventDefault(); //cancel the keypress
      }

      if ((text.indexOf('.') != -1) && (text.substring(text.indexOf('.')).length > 2) && //if there is a decimal point, and there are more than two digits after the decimal point
        ((element[0].selectionStart - element[0].selectionEnd) == 0) && //and no part of the input is selected
        (element[0].selectionStart >= element.val().length - 2) && //and the cursor is to the right of the decimal point
        (event.which != 45 || (element[0].selectionStart != 0 || text.indexOf('-') != -1)) && //and the keypress is not a -, or the cursor is not at the beginning, or there is already a -
        (event.which != 0 && event.which != 8)) { //and the keypress is not a backspace or arrow key (in FF)
        event.preventDefault(); //cancel the keypress
      }
    });
}

forceNumber($("#myInput"));