When you make a Janus room with JS, you can read the current state of your controller's buttons with these variables:
player.vive.left_trigger
player.vive.left_grip
player.vive.left_trackpad_x
player.vive.left_trackpad_y
player.vive.left_trackpad_click
player.vive.left_menu
player.vive.right_trigger
player.vive.right_grip
player.vive.right_trackpad_x
player.vive.right_trackpad_y
player.vive.right_trackpad_click
player.vive.right_menu
player.touch.left_trigger
player.touch.left_grip
player.touch.left_stick_x
player.touch.left_stick_y
player.touch.left_stick_click
player.touch.button_x
player.touch.button_y
player.touch.left_menu
player.touch.right_trigger
player.touch.right_grip
player.touch.right_stick_x
player.touch.right_stick_y
player.touch.right_stick_click
player.touch.button_a
player.touch.button_b
player.wmxr.left_trigger
player.wmxr.left_grip
player.wmxr.left_trackpad_x
player.wmxr.left_trackpad_y
player.wmxr.left_trackpad_click
player.wmxr.left_stick_x
player.wmxr.left_stick_y
player.wmxr.left_stick_click
player.wmxr.left_menu
player.wmxr.right_trigger
player.wmxr.right_grip
player.wmxr.right_trackpad_x
player.wmxr.right_trackpad_y
player.wmxr.right_trackpad_click
player.wmxr.right_stick_x
player.wmxr.right_stick_y
player.wmxr.right_stick_click
player.wmxr.right_menu
player.xbox.left_trigger
player.xbox.left_shoulder
player.xbox.left_stick_x
player.xbox.left_stick_y
player.xbox.left_stick_click
player.xbox.dpad_up
player.xbox.dpad_down
player.xbox.dpad_left
player.xbox.dpad_right
player.xbox.button_select
player.xbox.right_trigger
player.xbox.right_shoulder
player.xbox.right_stick_x
player.xbox.right_stick_y
player.xbox.right_stick_click
player.xbox.button_a
player.xbox.button_b
player.xbox.button_x
player.xbox.button_y
player.xbox.button_start
All variables are from 0(unpressed) to 1(pressed), except stick_x and stick_y. Those are from -1 (left and down) to 1 (right and up)