Anyone using a functional programming style in their Javascript?

a.) JavaScript makes it a bit of a pain to deep-copy objects; you can rig up something with $.extend and $.map, but it's not in the standard language the way Python's .copy() and [:] are

b.) Most of the time when you're doing JavaScript, the point is to change the state of the UI. Hard to write stateless code where the intended effect is to change state...

var fns = [];

function gensym() { return $R(0,20).toArray().map(function(){return String.fromCharCode(Math.random()*26+65)}).join('') }

function storefunc(f) { var g = gensym(); fns[g] = f; return 'fns.'+g }

function jsonk(url,hash,k) { var s = document.createElement('script');

  s.src = url+'?'+$H(hash).merge({'callback': storefunc(k)}).toQueryString();

  document.body.appendChild(s);

  return s.src

I learned gensym and web-read-k in Scheme at Brown (thanks, Shriram!), and jsonk turned out to be pretty useful, because the same comtinuation-passing style that's available when you do XHRs now becomes available when you do json requests from a different domain, if they have a callback parameter. (I brought this code to Songkick, and we shortened callback to k.)

 Urtog.score = new function() {
  this.init = function() {
    this.upmod; // boolean.  if increasing score, it's true; if decreasing, false.
    this.unit = 34;  // the pixel height of one digit
    this.digits = $$('div#scoredigits img.digit');  // array of all the digit images
  }

  /* change the score.  
   * first arg is the # of points to add or subtract (if negative).  
   * second arg is optional, specifies which digit img element to mod.  the default is the "1's" digit.
   */
  this.mod = function( points, digit ) {
    this.upmod = (points > 0);
    digit = digit || this.digits.last();
    var di = this.digits.indexOf(digit);
    var dy = (this.upmod ? 0-this.unit : this.unit);
    (Math.abs(points)).times(function(i) {
      new Effect.MoveBy(digit, dy, 0, {
        queue: {position:"end", scope:"d"+di},
        duration: 0.075,
        transition: Effect.Transitions.linear,
        beforeSetup: preroll.bind(Urtog.score)
      });
    })
  }

  /* the callback that's run before the digit is modded.  
   * does two things:
   * 1. resets the image strip to the top/bottom if necessary 
   * 2. checks if we should simultaneously mod the 10x digit (e.g. going from 09=>10 or 10=>09)
   */
  function preroll(effect) {
    var d = effect.element;
    var di = this.digits.indexOf(d);
    var offset = d.style.top;
    if (this.upmod) { // adding points
      if (offset=="-340px") { // at the bottom of the strip, so reset to the top
        d.style.top=offset="0px";
      }
      if (offset=="-306px") { // transitioning from 9=>0, so mod the 10x digit, too
        this.mod( 1, this.digits[di-1] );
      }
    }
    else { // subtracting points
      if (this.digits.all(function(d) { return is_zero(d.style.top); })) { // we've hit zero!
        Effect.Queues.instances.keys().each(function(k) {
          if (k.match(/d[0-9]*$/)) { // cancel all pending digit mods -- digit effect queue names are like d3,d2,d1
            Effect.Queues.instances[k].each(function(e) { 
              e.cancel() 
            }); 
          }
        });
        new Effect.UrtogShuffle('scoredigits');  // :)
        return false;
      }
      if (is_zero(offset)) { // at the top of the strip, so reset to the bottom
        d.style.top=offset="-340px";
      }
      if (offset=="-340px") { // transitioning from 0=>9, so mod the 10x digit, too
        this.mod( -1, this.digits[di-1] );
      }
    }
  }

  // account for bizarre safari behavior... wtf is "-0px"??
  function is_zero(offset) {
    return (offset=="0px" || offset=="-0px");  
  }
 } // end Urtog.score

www.flapjax-lang.org/

It uses the functional reactive pardigm where state can be implicitly updated without callbacks. Flapjax is compiled down to javascript, which makes a lot more sense than the functional javascript library which tries to make javascript into something it isn't.

osteele.com/sources/javascript/functional/