Allows only number keys, enter and full stop to be entered into an input[type=number] and ensures the format is that of a floating point number

number-format-ensurinator.js

(function() {
    "use strict";
    var els = document.querySelectorAll('input[type=number]');

    function makeKeypressEventHandler() {
        return function (e) {
            var keyCode = e.which || e.keyCode;

            if ((keyCode >= 48 && keyCode <= 57) ||
                    keyCode == 13 || keyCode == 46) {
                // Key is OK, but need to make sure that the number adheres to
                // the correct format (a digit optionally followed by a
                // decimal point and more digits)
                if ((this.value + String.fromCharCode(keyCode)).search(/^\d+(\.\d*)?$/) === 0) {
                    return;
                } else {
                    // console.log(String.fromCharCode(keyCode) + ", (" + keyCode + ")");
                    e.preventDefault();
                }
            } else {
                // console.log(String.fromCharCode(keyCode) + ", (" + keyCode + ")");
                e.preventDefault();
            }
        };
    }

    for (var i = 0; i < els.length; i++) {
        els[i].addEventListener('keypress', makeKeypressEventHandler());
    }
})();