A simple script to dump out the renderings in a Sitecore 8 / 9 instance. To use, login to the instance, expand the nodes under renderings you want to log and then execute this script in the console.

sc-renderings.js

var renderings = [];
var getName = function(el){
  return el.querySelector('a span').innerText;
}
var isFolder = function(el){
  return el.querySelector('a span img').src.indexOf('folder') !== -1;
}
var traverseTree = function(el, parentPath){
  parentPath = parentPath+"/"+getName(el);
  let children = el.children[3];
  if(children){
    children.childElements().forEach(function(child){
      var rendering = parentPath+"/"+getName(child);
      if(!isFolder(child)){
        renderings.push(rendering);
        console.log("Adding: "+rendering);
      } else {
        console.log("Skipping: "+rendering);
      }
      traverseTree(child, parentPath);
    });
  }
}
var root = null;
document.querySelectorAll('.scContentTreeNode').forEach(function(el){
  if(getName(el) === 'Renderings'){
    root = el;
  }
});
traverseTree(root, "");
console.log(renderings.join("\n"));