javascript:(function(document) {

function se(d) {

    return d.selection ? d.selection.createRange(1).text : d.getSelection(1)

} 

d = se(document); 

for (i=0; i<frames.length && (d==document || d=='document'); i++) d = se(frames[i].document); 

if (s || d=='document') d = prompt('Enter%20search%20terms%20for%20Wikipedia',''); 

open('https://en.wikipedia.org' + (s ? '/w/index.php?title=Special:Search&search=' + encodeURIComponent(s) : '')).focus();

})();