Question

I’m working on my first jQuery plugin which is a simple countdown timer with an option to set the target date. The goal is to get a plain text clock counting down to the provided target date & time. For the life of me I can’t figure out how to use setTimeout or setInverval within the plugin so it actually counts down. Spent all day digging through stackoverflow and other sources but couldn’t find a solution, so apologies if I’m just not getting it.

Here’s what I’ve got:

(function( $ ){

  $.fn.clock = function( options ) {  

    // ESTABLISH DEFAULTS
    var settings = $.extend( {
      'target' : '07/21/2013 09:00:00', // mm/dd/yyyy hh:mm:ss
    }, options);

    return this.each(function() {        

      // calculate milliseconds to target
      tarDate = new Date(settings.target);
      dateNow = new Date();
      amount  = tarDate.getTime() - dateNow.getTime();
      delete dateNow;

      // set label
      label = settings.title;

      // generate output
      if(amount <= 0) {
        out = '000:00:00:00';
      } else {
        td = 0; th = 0; tm = 0; ts = 0; out = ''; // reset everything
        amount = Math.floor(amount/1000);         // kill the milliseconds
        td     = Math.floor(amount/86400);        // calculate days to target
        amount = amount%86400;                    // convert amount to days
        th     = Math.floor(amount/3600);         // calculate hours to target
        amount = amount%3600;                     // convert amount to hours
        tm     = Math.floor(amount/60);           // calculate minutes to target
        amount = amount%60;                       // convert amount to minutes
        ts     = Math.floor(amount)+1;            // calculate seconds to target

    out += (td<=99?'0':'') + (td<=9?'0':'') + td + ':';
    out += (th<=9?'0':'') + th + ':';
    out += (tm<=9?'0':'') + tm + ':';
    out += (ts<=9?'0':'') + ts;
      }

      // assemble and pump out to dom
      $(this).html(out);

      // set refresh rate
      ??????

    });

  };
})( jQuery );

Answer 1

Check out this link for an interesting pattern for plugin authoring. Basically what you need to do is provide a “method” for updating your clock:

(function( $ ){

    function updateClock(element) {
        var settings = element.data("settings");
        // Your update logic goes here
    }

    $.fn.clock = function( options ) {  
        if ( options === 'update' )
            return updateClock(this);
        // Other methods, if any
        else if ( typeof options !== 'object' )
            throw 'Unknown method';

        // ESTABLISH DEFAULTS
        var settings = $.extend( {
            'target' : '07/21/2013 09:00:00', // mm/dd/yyyy hh:mm:ss
        }, options);

        // Save your settings for later access
        this.data("settings",settings);

Then, every time you want to update an element, you call it this way:

$(yourselector).clock("update");

(from outside; if updateClock is accessible from your scope, you can call it directly for efficiency. Just remember to wrap the element in $() if necessary)

Lastly, you have to configure setTimeout or setInterval. I would prefer setTimeout, because that will allow you to stop or restart your clock if necessary. Add this to the end of your updateClock, maybe preceeded by a check:

setTimeout(function() { updateClock(element); }, settings.refreshRate);