Deletes all Facebook friend requests, execute on https://www.facebook.com/friends/requests

gistfile1.js

var x = document.evaluate('//input[@value="Delete Request"]', document.documentElement, null, XPathResult.ANY_TYPE, null);
 
// gotta build an array of the elements, iterators throw exceptions if you modify the DOM from under them
var elements = [];
 
var thisNode = x.iterateNext();
while (thisNode) {
  elements.push(thisNode);
  thisNode = x.iterateNext(); 
}  
 
elements.forEach(function(e) {
  e.click();
});