DOM ISO.v.0.3.0.7.bookmarklet.js
bookmarklet for selecting and isolating an element on a page.

two sections:
section 1: Mouseover DOM, setup and handle mouse events and show information about element in informational div. Click to select, Any key to cancel.
section 2: Element Isolation with help of XPath. prompt user for XPath expression e.g., //DIV[@id='post-body']. then use XPath to select all elements not(ancestor or descendant or self), then delete those elements. also ignore self-or-descendants of head and title.

tools:
Ruderman's javascript development environment: https://www.squarefree.com/bookmarklets/webdevel.html#jsenv
Mielczarek's js to bookmarklet generator: http://ted.mielczarek.org/code/mozilla/bookmarklet.html

(function() {
	//GLOBALS
		//globals for classMausWork
		var gSelectedElement;	//currently only one selection
		var gHoverElement;		//whatever element the mouse is over
		var gHovering=false;	//mouse is over something
		var gObjArrMW=[];	//global array of classMausWork objects.  for removing event listeners when done selecting.
		
		//extended	
		var infoDiv;		//currently just container for InfoDivHover, might add more here
		var infoDivHover;	//container for hoverText text node.
		var hoverText;		//show information about current element that the mouse is over
		//const EXPERIMENTAL_NEW_CODE=true;	//debugging. new features.
	
	
	//START
	SetupDOMSelection();	



		
	//(Section 1) Element Selection
	function SetupDOMSelection()
	{

		{
			//setup event listeners
			//var pathx="//div | //span | //table | //td | //tr | //ul | //ol | //li | //p";
			var pathx="//div | //span | //table | //th | //td | //tr | //ul | //ol | //li | //p | //iframe";
			var selection=$XPathSelect(pathx);
			for(var element, i=0;element=selection(i);i++)
			{			
				if(element.tagName.match(/^(div|span|table|td|tr|ul|ol|li|p)$/i))	//redundant check.
				{
					var m = new classMausWork(element);
					gObjArrMW.push(m);
					attachMouseEventListeners(m);
				}
			}
			document.body.addEventListener('mousedown',MiscEvent,false);
			document.body.addEventListener('mouseover',MiscEvent,false);
			document.body.addEventListener('mouseout',MiscEvent,false);
			document.addEventListener('keypress',MiscEvent,false);
		}
		{
			//setup informational div to show which element the mouse is over.
			infoDiv=document.createElement('div');
			var s=infoDiv.style;
			s.position='fixed';
			s.top='0';
			s.right='0';
			
			s.display='block';
			s.width='auto';
			s.padding='0px';

			document.body.appendChild(infoDiv);
			infoDivHover=document.createElement('div');

			s=infoDivHover.style;
			s.fontWeight='bold';			
			s.padding='3px';
			s.Opacity='0.8';
			s.borderWidth='thin';
			s.borderStyle='solid';
			s.borderColor='white';
			s.backgroundColor='black';
			s.color='white';
			
			infoDiv.appendChild(infoDivHover);			
			hoverText=document.createTextNode('selecting');
			infoDivHover.appendChild(hoverText);
		}
	}
	
	function CleanupDOMSelection()
	{
		for(var m; m=gObjArrMW.pop(); )
		{
			detachMouseEventListeners(m);
		}
		ElementRemove(infoDiv);
		document.body.removeEventListener('mousedown',MiscEvent,false);
		document.body.removeEventListener('mouseover',MiscEvent,false);
		document.body.removeEventListener('mouseout',MiscEvent,false);		
		document.removeEventListener('keypress',MiscEvent,false);
	}	

	function attachMouseEventListeners(c)
	{
		//c is object of class classMausWork
		c.element.addEventListener("mouseover",c.mouse_over,false);				
		c.element.addEventListener("mouseout",c.mouse_out,false);	
		c.element.addEventListener("mousedown",c.mouse_click,false);		
	}

	function detachMouseEventListeners(c)
	{
		//c is object of class classMausWork
		c.resetElementStyle();
		c.element.removeEventListener("mouseover",c.mouse_over,false);				
		c.element.removeEventListener("mouseout",c.mouse_out,false);	
		c.element.removeEventListener("mousedown",c.mouse_click,false);		
	}

	//mouse event  handling class for element, el.
	function classMausWork(element)
	{	
		//store information about the element this object is assigned to handle. element,  original style, etc.	
		this.element=element;
		
		var elementStyle=element.getAttribute('style');
		var target;
		
		this.mouse_over=function(ev)
		{	
			if(gHovering)return;
			var e=element;			
			var s=e.style;
			s.backgroundColor='yellow';
			s.borderWidth='thin';
			s.borderColor='lime';
			s.borderStyle='solid';					
			InfoMSG(ElementInfo(e),'yellow','blue','yellow');
			gHoverElement=e;
			gHovering=true;
			target=ev.target;
			ev.stopPropagation();		
		};
		
		this.mouse_out=function(ev)
		{
			if(!gHovering)return;
			if(gHoverElement!=element ||ev.target!=target)return;
			var e=element;
			e.setAttribute('style',elementStyle);
			InfoMSG('-','white','black','white');	
			gHoverElement=null;
			gHovering=false;
			target=null;
			//ev.stopPropagation();
		};
		
		this.mouse_click=function(ev)
		{
			if(!gHovering)return;
			if(gHoverElement!=element ||ev.target!=target)return;
			var e=element;
			e.setAttribute('style',elementStyle);
			ev.stopPropagation();			
			CleanupDOMSelection();			
			gHoverElement=null;
			gHovering=false;
			target=null;
			
			if(ev.button==0)
			{
				gSelectedElement=e;
				ElementSelected(e);	//finished selecting, cleanup then move to next part (section 2), element isolation.
			}
		};
		
		this.resetElementStyle=function()
		{
			element.setAttribute('style',elementStyle);
		};		
	}

	function MiscEvent(ev)		//keypress, and mouseover/mouseout/mousedown event on body.  cancel selecting.
	{
		if(ev.type=='mouseout' && !gHovering)
		{
			InfoMSG('-','white','black','white');
		}
		else if(ev.type=='mouseover' && !gHovering)
		{
			InfoMSG('cancel','yellow','red','yellow');
		}
		else //keypress on document or mousedown on body, cancel ops.
		{
			CleanupDOMSelection();
		}
	}
	
	function InfoMSG(text,color,bgcolor,border)
	{
		
		var s=infoDivHover.style;
		if(color)s.color=color;
		if(bgcolor)s.backgroundColor=bgcolor;
		if(border)s.borderColor=border;
		if(text)hoverText.data=text;
	}
	


	
	
	//(Section 2) Element Isolation
	function ElementSelected(element)	//finished selecting element.  setup string to prompt user.
	{
		PromptUserXpath(ElementInfo(element));
	}
	
	
	function PromptUserXpath(defaultpath)		//prompt user, isolate element.
	{
		var userpath = prompt("XPath of elements to isolate : ", defaultpath);
		if(userpath && userpath.length>0)
		{
			var addPredicate = "[count(./ancestor-or-self::head)=0][count(./ancestor-or-self::title)=0]";	//exclude head & title elements from selection so they aren't removed
			var addPath = "//script | //form | //object | //embed";	//include these elements in selection for removal
			var pathx=TransformXPath_NoAncestorDescendentSelf(userpath, addPredicate, addPath);		//the xpath selection of all elements to be removed/deleted.
			
			try
			{
				var element;
				var elements=$XPathSelect(pathx);	
				for(var i=0;element=elements(i);i++)
				{			

					if(!element.nodeName.match(/^(head|title)$/i))	//redundant check.
					{
						ElementRemove(element);
					}
				}
			}
			
			catch(err)
			{
				alert("wtf: "+err);
			}
			
		}
	}
	
		
	
	//support
	function $XPathSelect(p, context) 
	{
	  if (!context) context = document;
	  var i, arr = [], xpr = document.evaluate(p, context, null, XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE, null);
	  return function(x) { return xpr.snapshotItem(x); };	//closure.  wooot!  returns function-type array of elements (usually elements, or something else depending on the xpath expression).
	}
	
	function ElementRemove(e)
	{
		if(e)e.parentNode.removeChild(e);
	}
	
	function ElementInfo(element)
	{
		var txt='';
		if(element)
		{
			txt=element.tagName.toLowerCase();		//txt=element.tagName;
			txt=attrib(txt,element,'id');
			txt=attrib(txt,element,'class');	
			txt='//'+txt;
		}
		return txt;
		
		function attrib(t,e,a)
		{			
			if(e.hasAttribute(a))
			{
				t+="[@"+a+"='"+e.getAttribute(a)+"']";
			}
			return t;
		}
		
	}


	
	//function to 'invert' the XPath by selecting all elements that are not ancestor and not descendent and not self.
	function TransformXPath_NoAncestorDescendentSelf(u, includePredicates, includePaths)
	{	
		
		//sample input (u):					//div[@class='sortbox']
		//sample output						//*[  not(./descendant-or-self::*=//div[@class='sortbox'])][  not(./ancestor-or-self::*=//div[@class='sortbox'])]
		//sample output with additional conditions:		//*[  not(./descendant-or-self::*=//div[@class='sortbox'])][  not(./ancestor-or-self::*=//div[@class='sortbox'])][count(./ancestor-or-self::head)=0][count(./ancestor-or-self::title)=0]
		
			//obsolete method.  much faster but can only be used for limited types of (simple) xpath expressions -- unlike the current version, which should be able to convert any xpath.
			//input:			table[@id='topbar']
			//output:			//*[not(./descendant-or-self::table[@id='topbar']) and not(./ancestor-or-self::table[@id='topbar'])]
			//output (alternative):	//*[count(./descendant-or-self::table[@id='topbar'])=0 and count(./ancestor-or-self::table[@id='topbar'])=0]
		
		
		var o1=	'./descendant-or-self::*='+gr(u);
		o1=	'not' + gr(o1);
		o1=	nt(o1);	
		var o2= './ancestor-or-self::*='+gr(u);
		o2=	'not' + gr(o2);
		o2=	nt(o2);

		var o=	'//*'+o1+o2;
		if(includePredicates && includePredicates.length>0)	o += includePredicates;
		if(includePaths && includePaths.length>0) o += ' | ' + includePaths;
		return o;
		
		
		function nt(term){return wrap(term,'[]');}	//node test; predicate - enclose with bracket.
		function gr(term){return wrap(term,'()');}	//group - parenthesize.
		function wrap(term, enclosure){return enclosure.charAt(0)+term+enclosure.charAt(1);}
	}	
	


	
})();

This only works with the IE browsers. Add this code within your <head> tags. To keep the underline on your links, replace "none" with "underline" Change "YourColor" with the hexidecimal number of color required.
Find this and other snippets on my site, if you wish, by clicking here

<style
type="text/css"> <!-- A:link { text-decoration: none; color:#YourColor
} A:visited { text-decoration: none; color:#YourColor } A:hover { text-decoration:
none; color:#YourColor } --> </style>