Recently, I've been working on a video game with Three.js and I want the up arrow key to go forward relative to the camera.

Here is my code for the arrow key.

var x = 0;
var rotx = 0;
setInterval(function() {
    if (x == 1){
        camera.position.z += 0.05
    }
}

    document.addEventListener("keydown", function(event){
        if (event.key == "ArrowUp"){
            x = 1
        }
    });
    document.addEventListener("keyup", function(event){
        if (event.key == "ArrowUp"){
            x = 0
        }
});

Many times I've been searching for the answer. Usually coming across both

object.localToWorld();
object.worldToLocal();

but I can't seem to understand how to use this method.