I'm using the Javascript Date(string) constructor with a date format of "yyyy-mm-dd". The constructor works just fine in IE 9 and Firefox unless the app is running on our testing VM which is running IIS. If it's on the VM, in IE 9 it returns 'NaN', but still works normally in Firefox.

    var dateAsString = "2011-11-09";
    var dateCreated = new Date(dateAsString);

I was under the assumption that the server had nothing to do with client-side Javascript. Any suggestions?

I'm using the Javascript Date(string) constructor with a date format of "yyyy-mm-dd". The constructor works just fine in IE 9 and Firefox unless the app is running on our testing VM which is running IIS. If it's on the VM, in IE 9 it returns 'NaN', but still works normally in Firefox.

    var dateAsString = "2011-11-09";
    var dateCreated = new Date(dateAsString);

I was under the assumption that the server had nothing to do with client-side Javascript. Any suggestions?

• javascript
• internet-explorer
• iis
• date

• Pretty sure that the server has nothing to do with client-side Javascript as the client (the person visiting the site) runs that code, not the server. – jakx Commented Nov 11, 2011 at 19:37
• @jakx I know, that's why I am confused by this. – Gagege Commented Nov 11, 2011 at 19:47
• 2 Check the document mode in the developer tools of IE (F12) on both servers. I suspect they differ. – Phrogz Commented Nov 11, 2011 at 19:57
• @Phrogz wins! Thanks. Now I can sleep tonight! – Gagege Commented Nov 11, 2011 at 20:02

4 Answers 4

And for those of us who want to know how to replace hyphens (aka dashes) with slashes:

new Date(dashToSlash(string));

That uses this function:

function dashToSlash(string){
  var response = string.replace(/-/g,"/");
  //The slash-g bit says: do this more than once
  return response;
}

In my case it's much easier to convert hyphens to slashes selectively (only where it's needed for the Date() function) than to replace the date format everywhere in my code.

Note: you really need to define a separate 'response' variable and assign it the value of the replace operation result. If you don't, the string is returned unaltered in Chrome. That's not a huge problem, since Chrome doesn't have a problem with hyphenated date strings to begin with. But still...

Just use slashes instead of hyphens if you can.

EDIT: Expanded clarification...

The ISO 8601 standard format uses the hyphen as a date separator. My answer does not mean you do not need to follow standards. You can use slashes only for the Date constructor if necessary.

It's because of the date format. For some reason, IE and Safari get tripped up with yyyy-mm-dd. Use another date format and you should be all set.

It's talked about here:
http://biostall.com/javascript-new-date-returning-nan-in-ie-or-invalid-date-in-safari

I suggest attempting a more reliable form of date parsing. The example below uses setFullYear(). Does IE produce a different result with the code below?

/**Parses string formatted as YYYY-MM-DD to a Date object.
   * If the supplied string does not match the format, an 
   * invalid Date (value NaN) is returned.
   * @param {string} dateStringInRange format YYYY-MM-DD, with year in
   * range of 0000-9999, inclusive.
   * @return {Date} Date object representing the string.
   */
  function parseISO8601(dateStringInRange) {
    var isoExp = /^\s*(\d{4})-(\d\d)-(\d\d)\s*$/,
        date = new Date(NaN), month,
        parts = isoExp.exec(dateStringInRange);

    if(parts) {
      month = +parts[2];
      date.setFullYear(parts[1], month - 1, parts[3]);
      if(month != date.getMonth() + 1) {
        date.setTime(NaN);
      }
    }
    return date;
  }

Source: http://jibbering.com/faq/#parseDate