Mongo Search & Replace

gistfile1.js

var cursor = db.collection.find(url: /http/) 
while (cursor.hasNext()) {
  var x = cursor.next();
  print("Before: "+x['url']);
  x['url'] = x['url'].replace('http', 'https');
  print("After: "+x['url']);
  db.collection.update({_id : x._id}, x);
}