Iterations, anyone? AKA How I wrote a walk_dom method.

walk_dom.js

// Iterations, anyone? AKA
// How I wrote a walk_dom method.
// 
// A JavaScript poem by
// 
// "Cowboy" Ben Alman
// 11/21/2009

// A starting point.

function walk_dom( node, callback ) {
  var cur = node, skip;
  do {
    if ( !skip && cur.firstChild ) {
      cur = cur.firstChild;
    } else if ( cur.nextSibling ) {
      cur = cur.nextSibling;
    } else {
      skip = true;
      cur = cur.parentNode;
      continue;
    }
    skip = false;
    callback( cur );
    
  } while ( cur !== node );
};

// Using a temp variable.

function walk_dom( node, callback ) {
  var cur = node, skip, temp;
  do {
    if ( !skip && ( temp = cur.firstChild ) ) {
      cur = temp;
    } else if ( temp = cur.nextSibling ) {
      cur = temp;
    } else {
      skip = cur = cur.parentNode;
      continue;
    }
    skip = 0;
    callback( cur );
    
  } while ( cur !== node );
};

// Removing that redundant "else if".

function walk_dom( node, callback ) {
  var cur = node, skip, temp;
  do {
    if ( !skip && ( temp = cur.firstChild ) || ( temp = cur.nextSibling ) ) {
      skip = 0;
      callback( cur = temp );
    } else {
      skip = cur = cur.parentNode;
    }
    
  } while ( cur !== node );
};

// Let the callback skip the current node by returning false.

function walk_dom( node, callback ) {
  var cur = node, skip, temp;
  do {
    if ( !skip && ( temp = cur.firstChild ) || ( temp = cur.nextSibling ) ) {
      skip = callback( cur = temp ) === false;
    } else {
      skip = cur = cur.parentNode;
    }
    
  } while ( cur !== node );
};

// Wow, cool! Now I can simplify that if/else into a ternary.

function walk_dom( node, callback ) {
  var cur = node, skip, temp;
  do {
    skip = !skip && ( temp = cur.firstChild ) || ( temp = cur.nextSibling )
      ? callback( cur = temp ) === false
      : cur = cur.parentNode;
    
  } while ( cur !== node );
};

// It's all done now, but just for the sake of argument..

// Organized for smallest minification size.

function walk_dom( node, callback, cur, skip, temp ) {
  cur = node;
  do {
    skip = !skip && ( temp = cur.firstChild ) || ( temp = cur.nextSibling )
      ? callback( cur = temp ) === !1
      : cur = cur.parentNode;
    
  } while ( cur !== node );
};

// Minified!

(function(w,a,l,k,r){l=w;do{k=!k&&(r=l.firstChild)||(r=l.nextSibling)?a(l=r)===!1:l=l.parentNode}while(l!==w)})(node,callback);

How about less ROFLS and more WALKR?

Great idea, done!

New, better DOM walker