isNumber.js

/**
 * Determine whether the supplied value's datatype is Number
 * @param {Mixed} value Could be a true number: 123, 12.00, or eg: "123", "12.00" 
 * @return {Boolean} Whether value's type is Number, eg: "123" would be false whereas 123 would be true.
 */
function isNumber(data)
{
    var num = parseFloat(data);
    return ! isNaN(parseFloat(data)) && num.toString() === data.toString();
}