3 Data validation methods in javascript

Function is isValideDate can be used for example on a string data.isValideDate() to confirm that date is in correct format like these 2 for example:

  • 04-11-2012
  • 4-11-12

The isNumeric function is used same way with data.isNumeric() on a string and the function is used validation if the whole input is numeric

<pre class="brush: jscript; title: ; notranslate" title="">String.prototype.isValidDate = function()
    var IsoDateRe = new RegExp("^([0-9]{2})-([0-9]{2})-([0-9]{4})$");
    var matches = IsoDateRe.exec(this);
    if (!matches) return false;
    var composedDate = new Date(matches[3], (matches[2] - 1), matches[1]);
    return ((composedDate.getMonth() == (matches[2] - 1)) &&
        (composedDate.getDate() == matches[1]) &&
        (composedDate.getFullYear() == matches[3]));

String.prototype.isNumeric = function () {
    var intRegex = /^\d+$/;

    var v = this;

    if(intRegex.test(v)) {
        return true;
    return false;

And just for you, a third function for strings. This function data.isDouble() checks if the inputed data is of a double type.

<pre class="brush: jscript; title: ; notranslate" title="">String.prototype.isDouble = function () {
    var validChars = '0123456789.';

    for(var i = 0; i &lt; this.length; i++) {
        if(validChars.indexOf(this.charAt(i)) == -1)
            return false;
    var dblVar = parseFloat(this);

        return false;
    return true;;
Matjaz Trcek
Matjaz Trcek
SRE @ Magnolia CMS

Working as an SRE in Magnolia CMS. In my free time I work on many side projects some of which are covered in this blog.