Add an edit link for tumblr posts (very useful for colaborative blogs)

Tumblr.user.js

// ==UserScript==
// @name           Tumblr - Edit link
// @namespace      ivanmendoza.net
// @description    Add an edit link for tumblr posts (very useful for colaborative blogs)
// @include        http://jser.info/post/*
// ==/UserScript==
// origina from http://userscripts.org/scripts/show/65725
function getLink() {
    var href = location.href;
    var m = new RegExp('(http:\\/\\/)((?:[a-z][a-z\\.\\d\\-]+)\\.(?:[a-z][a-z\\-]+))(?![\\w\\.])(\\/post\\/)(\\d+)', ["i"]).exec(href);
    var userID = m[m.length - 1];
    return ("http://www.tumblr.com/edit/" + userID + "?redirect_to=" + encodeURIComponent(href));
}
function addLink() {
    var edit_page = getLink();
    var eLink = document.createElement("a");
    eLink.setAttribute("id", "edit_link");
    eLink.setAttribute("style", "position:absolute;top:5px;left:2px;padding:2px 0 0;width:40px;height:18px;display:block;overflow:hidden;-moz-border-radius:3px;background:#777;color:#fff;font-size:8pt;text-decoration:none;font-weight:bold;text-align:center;line-height:12pt;");
    eLink.setAttribute("href", edit_page);
    eLink.appendChild(document.createTextNode("Edit"));
    var elBody = document.getElementsByTagName("body")[0];
    elBody.appendChild(eLink);
}
addLink();