Get XML file, based on current date

I am very new to parsing XML data with javascript, so please excuse me if my question is a bit simple.

I am parsing data from an XMl file with javascript using a standard xmlHTTPRequest. The format of th开发者_如何转开发e URL that I am pulling the XML data from is something like: "http://example.com/abcyymmdd-data.xml". The (yymmdd) portion of the url represents the date and the files are updated daily. I would like to insert a javascript code in the url in place of yymmdd so that a new XML file is parsed each day. How might I achieve this?

Thanks, Carlos

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First, to get today's date, use:

var today = new Date;

To get the components, use:

var date  = today.getDate();
var month = today.getMonth() + 1; // caveat, starts at 0
var year  = today.getFullYear();  // 4 numbers (e.g. 2011)

Now, you need it in the format yymmdd. So you need to remove the two first numbers from year, and prepend a 0 to date and month, if necessary.

function zeropad(number) {
    var str = number.toString(); // number to string

    return str.length === 1 // if length is 1
            ? '0' + str     // prepend a 0
            : str;          // otherwise return string without modification
}

And then:

var formatted = year.toString().substring(2) // only the string from the first two numbers and on
                 + zeropad(month)            // month with 0 prepended
                 + zeropad(date);            // date with 0 prepended

Then, in your XHR, use:

xhr.open("GET", "http://example.com/abc" + formatted + "-data.xml", true);

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You can retrieve the current date in yymmdd format like:

var d = new Date();
var date_string = 
    d.getFullYear().toString().substring(2) +
    (d.getMonth () < 9 ? "0" : "") + (d.getMonth() + 1) +
    (d.getDate() < 10 ? "0" : "") + d.getDate();

Example at JS Fiddle.