Hi, Thank to @sparx for reply as C#.
and as JS, use this form of script:
/// This form you can get input of your keybind, 0x4C is "L", you can change it to your own key code everything you want.
mp.keys.bind(0x4C, true, function() {
/// Here write your code as you wish
});
Finally, use this hyper link to find the key code you want