Throttle + Debounce

throttle_debounce.js

/*!
 * Throttle + Debounce - v0.2 - 2/5/2010
 * http://benalman.com/
 * 
 * Copyright (c) 2010 "Cowboy" Ben Alman
 * Dual licensed under the MIT and GPL licenses.
 * http://benalman.com/about/license/
 */

// Returns a function that will, when called repeatedly, execute `callback` no
// more than once every `delay` milliseconds. After the function stops being
// called, it will execute one final time after approximately `delay`
// milliseconds (but only if necessary). If delay is 0 or omitted, `callback`
// will execute every time.

function throttle_debounce( callback, delay ) {
  var timeout_id,
    last_updated = 0;
  
  return function() {
    var now = +new Date,
      that = this,
      args = arguments;
    
    function fn() {
      callback.apply( that, args );
    };
    
    if ( !delay || now - last_updated  > delay ) {
      last_updated = now;
      fn();
    } else {
      timeout_id && clearTimeout( timeout_id );
      timeout_id = setTimeout( fn, delay );
    }
  };
};

/*

// Example:

$(function(){
  
  function log_coords(e) {
    console.log( e.pageX + ',' + e.pageY );
  };
  
  $('body').mousemove( throttle_debounce( log_coords, 1000 ) );
  
});

*/