Wikipedia:Tools/View source

// VIEW SOURCE addOnloadHook(function {  if (location.href.indexOf('viewsource=1') != -1) {    sl = document.getElementById('wpSummaryLabel'); sl.parentNode.removeChild(sl);    ed = document.getElementById('wpSummary').parentNode; ed.parentNode.removeChild(ed);    return;  }  editbutton = document.getElementById('ca-edit');  if (editbutton && location.href.indexOf('action=edit')==-1) {    editlink = editbutton.getElementsByTagName('a')[0].href + '&viewsource=1';    tabs = document.getElementById('p-cactions').getElementsByTagName('ul')[0];    na = document.createElement('a');    na.href = editlink; na.appendChild(document.createTextNode('view source'));    li = document.createElement('li'); li.id = 'ca-viewsource'; li.appendChild(na);    tabs.insertBefore(li,editbutton);  } });