Ver o Código-fonte com Java Script

É mais uma coisa inútil que agente acha por ai, em qualquer página digite(nao digite, copie e cole, é gigantesco) isso aqui:

javascript:var%20sourceWindow%3Dwindow.open%28%27about%3Ablank%27%29%3B%0Avar%20newDoc%3DsourceWindow.document%3B%0AnewDoc.open%28%29%3B%0AnewDoc.write%28%27%3Chtml%3E%3Chead%3E%3Ctitle%3ESource%20of%20%27%2Bdocument.location.href%2B%27%3C/title%3E%3Cmeta%20name%3D%22viewport%22%20id%3D%22viewport%22%20content%3D%22initial-scale%3D1.0%3B%20user-scalable%3D0%3B%20maximum-scale%3D0.6667%3B%20width%3D480%22/%3E%3Cscript%3Efunction%20do_onload%28%29%7BsetTimeout%28function%28%29%7Bwindow.scrollTo%280,1%29%3B%7D,100%29%3B%7Dif%28navigator.userAgent.indexOf%28%22iPhone%22%29!%3D-1%29window.onload%3Ddo_onload%3B%3C/script%3E%3C/head%3E%3Cbody%3E%3C/body%3E%3C/html%3E%27%29%3B%0AnewDoc.close%28%29%3B%0Avar%20pre%3DnewDoc.body.appendChild%28newDoc.createElement%28%22pre%22%29%29%3B%0Apre.appendChild%28newDoc.createTextNode%28document.documentElement.innerHTML%29%29%3B

Pra quê serve isso? Sei lá! Mais é legal