How do i on the y axis my camera from moving?

I a making 3D game where i use WASD to rotate the camera and arrow keys to move. i used this script for movement.

var speed : float = 5; //Controls the movement speed of the camera var x : float; var z : float;

function Update () {

x = Input.GetAxis("MoveX") speed Time.deltaTime; //calculates the cameras side to side movement

z = Input.GetAxis("MoveY") speed Time.deltaTime; //calculates the cameras forward back movements

transform.Translate(x, 0, z); //moves the camera according to the values calculated previously

}

It works, but when you are looking upwards and move, it moves with the camera upward, instead of straight forward. If it is relevant here is the camera look script also

var yMaxLimit = 80;

private var x = 0.0; private var y = 0.0;

@script AddComponentMenu("Camera-Control/Mouse Orbit")

function Start () { var angles = transform.eulerAngles; x = angles.y; y = angles.x;

 // Make the rigid body not change rotation
 if (rigidbody)
     rigidbody.freezeRotation = true;

}

function LateUpdate () {

     x += Input.GetAxis("LookX") * xSpeed * 0.02;
     y -= Input.GetAxis("LookY") * ySpeed * 0.02;
 
     y = ClampAngle(y, yMinLimit, yMaxLimit);
 
     var rotation = Quaternion.Euler(y, x, 0);
 
     transform.rotation = rotation;

}

static function ClampAngle (angle : float, min : float, max : float) { if (angle < -360) angle += 360; if (angle > 360) angle -= 360; return Mathf.Clamp (angle, min, max);

}