finds <p>'s within a given context of a web page

seekingParagraphs-2.js

(function(){
  var context = arguments[0] || document.body
  //, nodes = context.childNodes, nLen = nodes.length
  , ctxParagraphs = [], ctxConditions = false
  , ELM_NODE = 1, TXT_NODE = 3;//, HTML_COMMENT_NODE = 8

  function hasClass(ctx, cls) {
    return ctx.className 
      && new RegExp(
        '(^|\\s)' + cls + '(\\s|$)'
      )
      .test(ctx.className);
  }

  function seek(ctx) {
    if (ctxConditions) return;

    var tryClass = arguments[1] ? arguments[1] : false
    , isElement = ctx.nodeType == ELM_NODE
    , isClassed = hasClass(ctx, tryClass);

    //if (tryClass) console.log('seeking .'+tryClass);
    ctxConditions = isElement && tryClass && isClassed;
    /*
      // is element node AND not attempting to match class:
      (isElement && !tryClass)
      || // OR
      // is element node AND attempting class match AND found match:
      (isElement && tryClass && isClassed)
    ;*/
     
    if ( ctxConditions ) {
      // found a useful class-scoped context, use it and get out!
      ctxParagraphs = ctx.getElementsByTagName('p');//console.log('context conditions met!');
      return;
    }
    else {//recurse
      for (var i=0, l = ctx.childNodes.length; i < l; ++i) {
        switch (ctx.childNodes[i].nodeName.toLowerCase()) {
          case 'div':
            seek(ctx.childNodes[i], tryClass);
            break;
        }
      }
    }
  }

  // seek known content #id markers...
  // @todo
  
  // seek known content .class markers...
  try {
    seek(context, 'birdie');  // miss
    seek(context, 'fuckwad'); // miss
    seek(context, 'gimmeh');  // miss
    seek(context, 'post');    // hit! (wordpress)
  }
  catch(e) {;}
  
  // if no narrower context was discovered, operate on all <p>'s:
  if (ctxParagraphs.length == 0) {
    //seek(context);
    ctxParagraphs = context.getElementsByTagName('p');
  }

  var pLen = ctxParagraphs.length; //console.log(pLen); console.log(postParagraphs);
  while(pLen--) {
    // do shit!
    ctxParagraphs[pLen].style.textDecoration = 'line-through';
  }

}())

seekParagraphs.js

(function(){
  var context = arguments[0] || document.body
  , pNodes = [], txtNodes = []
  , ELM_NODE = 1, TXT_NODE = 3//, HTML_COMMENT_NODE = 8
  , whitespace = /^\s*$/;

  // more useful!
  function seekParaNodes(ctx) {
    if (ctx.nodeType == ELM_NODE && ctx.nodeName == 'P') {
        pNodes.push(ctx); //console.log(ctx.textContent);
    }
    else {//recurse
      for (var i=0, l = ctx.childNodes.length; i < l; ++i) {
        seekParaNodes(ctx.childNodes[i]);
      }
    }
  }

  // less useful
  function seekTextNodes(ctx) {
    if (ctx.nodeType == TXT_NODE) {
      if (whitespace.test(ctx.nodeValue)) {
        txtNodes.push(ctx);//console.log(ctx.textContent);
      }
    }
    else {//recurse
      for (var i=0, l = ctx.childNodes.length; i < l; ++i) {
        seekTextNodes(ctx.childNodes[i]);
      }
    }
  }

  seekParaNodes(context);
  console.log(pNodes);
}(/*document.getElementById('post-155442')*/))

this answer on stackoverflow helped out with the seekTextNodes() approach using native DOM methods.