delegate-refactor.js

// BEFORE
// http://jsfiddle.net/markcoleman/ffBcU/11/

var currentColor = "white";
var hold = false;

$(".canvas")
  .delegate(".pixel", "mouseover", function() {
    $(this).css("background-color", currentColor);
  })
  .delegate(".pixel", "mouseout", function() {
    if (!$(this).data("painted")) {
      $(this).css("background-color", "");
    }
    if ($(this).data("painted")) {
      $(this).css("background-color", $(this).data("painted"));
    }
  })
  .delegate(".pixel", "mousedown", function() {
    hold = true;
    $(this).css("background-color", currentColor).data("painted", currentColor);
  })
  .delegate(".pixel", "mouseup", function() {
    hold = false;
  })
  .delegate(".pixel", "mousemove", function(e) {
    if (hold) {
      var elem = document.elementFromPoint(e.pageX, e.pageY);
      if ($(elem).is(".pixel")) {
        $(elem).css("background-color", currentColor).data("painted", currentColor);
      }
    }
  });

// AFTER
// http://jsfiddle.net/cowboy/ffBcU/12/

var currentColor = "white";
var hold = false;

$(".canvas")
  .delegate(".pixel", "mouseover mouseout", function( e ) {
    var color = e.type == "mouseover" ? currentColor : $(this).data("painted") || "";
    $(this).css("background-color", color);
  })
  .delegate(".pixel", "mousedown mouseup", function( e ) {
    hold = e.type == "mousedown";
  })
  .delegate(".pixel", "mousedown mousemove", function() {
    hold && $(this).css("background-color", currentColor).data("painted", currentColor);
  });