Getting info from another page using ajax

[rnd me]

One question i see on here a lot is "how do i pull a div on a different page into the current page?"

The responses are often complex or they pass the buck: try using jQuery, use PHP, use a CMS, double-code both divs, etc...

I didn't like any of those answers, and knew it couldn't be that difficult to do with a tiny bit of javascript. There really is no short answer, until now.

function getPage(url, from, to) {
	var cached=sessionStorage[url];
   	if(!from){from="body";} // default to grabbing body tag
	if(cached){return elm.innerHTML=cached;} // cache responses for instant re-use re-use
	if(to && to.split){to=document.querySelector(to);} // a string TO turns into an element
	if(!to){to=document.querySelector(from);} // default re-using the source elm as the target elm

	var XHRt = new XMLHttpRequest; // new ajax
	XHRt.responseType='document';  // ajax2 context and onload() event
	XHRt.onload= function() { sessionStorage[url]=to.innerHTML= XHRt.response.querySelector(from).innerHTML;};
	XHRt.open("GET", url, true);
	XHRt.send();
	return XHRt;
}

ARGUMENTS:

getPage(
  URL :    Location of remote resource , 
  FROM : CSS selector of source tag on remote page , 
  TO:      CSS selector of destination tag
)

the source defaults to "body" if the from CSS selector is not specified, and the to CSS selector defaults to the from value if not specified.

Example uses:

EX 1. (typical use) virtually grab the next page:
when on http://www.codingforums.com/forumdisplay.php?f=2
show table from http://www.codingforums.com/forumdis...er=desc&page=2

getPage("/forumdisplay.php?f=2&order=desc&page=2",
  "#inlinemodform", 
  "#inlinemodform" );

notice how "#inlinemodform" is repeated? It's moving the same block to the same block on another page.
You can omit the 2nd CSS selector when it's a duplicate, so the following is 100% equivalent to the above:

getPage("/forumdisplay.php?f=2&order=desc&page=2",
  "#inlinemodform" );

EX 2. (defaults) replace this whole page with another post i wrote a while back:

getPage("http://www.codingforums.com/showthread.php?t=281163")

EX 3. (external content) inject event listings from UIUC into the current page:

getPage("//www.it.illinois.edu/news/", ".list.events.vcard.clearfix", ".tcat" )