Quick Edit for Blogger Themes without quick edit enabled

The almighty quick edit

Create a HTML/Javascript Widget to the footer, and add this code:
<span class="item-control blog-admin">
onclick="blogQuickEdit()" style="display: block;text-align:
center;"><img alt='' class='icon-action' height='18'
// https://cl.mt/blog/new-blogger-theme-quick-editing
function blogQuickEdit() {
var str = document.getElementsByTagName('html')[0].innerHTML;
var w;
var urla = window.location.href
var v = str.split("targetBlogID=")[1];
w = v.substring(0, v.indexOf("&"));
var r = str.split("postID=")[1];
var z = r.substring(0, r.indexOf("&"))
if (z.length > 19) { //legacy support
r = str.split("feeds/")[4];
z = r.substring(0, r.indexOf("/"));
var url = "https://www.blogger.com/blog/post/edit/" + w + "/" + z;
window.open(url, '_blank');
Modified from Clement Ong's work to work on a website rather than a bookmark, and use the new blogger editor as of 2020.

DISCLAIMER: I'm lazy and only set this up to quick edit posts. It will fail for pages.