JQuery game I am making

Hello, I have recently been making a JQuery game. I need to make it so when your holding down a key to move your character an animation starts, but when you let go the animation stop's. I have already made the character changes when you move and stuff, just need the animation to stop when you let go. I also need you to possibly show me how to make a wall in Jquery that your character can not pass, or you can show me how to make it so when two div's get within a certain range of each other something happens. I also need someone to make me a character for my game, I will provide more information on that and will need about 3 character's. -Thanks, Liam