The TJ door straps take a lot of abuse and over time can break or stretch out, dealing with a door that won’t stay in place when open is annoying and a potential for damage. The door can strike the front of the Jeep damaging the mirror, flare or cowl area. Luckily there are several replacement options from fancy to simple and inexpensive.
Our 2004 TJ Unlimited straps, which are probably original, definitely have seen better days so we picked up a set of replacements from Quadratec and replaced them. This is a quick job really and only requires a torx socket.
Secure the door to prevent it from swinging all the way forward if needed. With the Jeep side of the strap removed remove one of the torx bolts from the door hoop and loosen the bottom to allow it to rotate. Pull off the strap.
Now put the new strap back on the hoop and tighten back up the bolts. Done!
adjustable loops 
It’s little upgrades like this that keep your old Jeep feeling fresh.