Does anyone have any tips to prevent your Chi from bolting for the door when you open it?

Today is the first day that Jaxx has done this but I want to nip it in the bud so to speak before he starts doing it every time we go outside.

Before today he stayed clear away from the door unless he was on his leash. I blame myself because I knew he was hyper and wanted to play but I had an appointment and had to leave and I had just taken him outside so that he could stay in the living room while I was gone.

I think he probably knew I was leaving and wanted to go with me or just really wanted to play. When I told him to stop he did stop but it worried me that he almost ran out into the parking lot where someone could easily have hit him.

After I told him that it was "bad" he did not attempt to come near the door when I left or came back but I am afraid he will do it again.

I was going to put him in his cage so he would not try it again when I left or came back but I did not want him to think I was punishing him by putting him in his cage so I took the chance that he would not try it again and luckily he did not.

I have never had a dog run for the door so I have no idea how to correct the problem. When I told my boyfriend he said his previous dog had done it and he just caught him whenever it happened but I would like to prevent it from happening without having to cage him every time we leave.

Charlie did this twice and got outside both times. I caught him both times but it was scary.

What I did was teach him to sit when the door is opened. I put him on his leash and went to the door with him. I dropped the leash and put my foot on it giving him plenty of slack. Give the command sit and then open the door quickly offering a treat if he stayed seated. Also any time I take him out on the leash, I make him sit, then I go through the door first and tell him okay when he can come out. We still watch him closely but now even when he's not on a leash the sit command keeps him from dashing out the door.