Im trying to make a character jump when a GUI button is clicked on

Hello, I am trying to make a player with a character controller jump when a button is clicked onscreen however the character will not jump. Here is my code so far
var speed : float = 3.0;
var rotateSpeed : float = 3.0;
var moveJoystick : Joystick;
var rotateJoystick : Joystick;
var jumpSpeed : int =5;
var gravity : int = 32;
private var moveDirection : Vector3 = Vector3.zero;
private var grounded = false;

function Update () {
    var controller : CharacterController = GetComponent(CharacterController);
 
    // Rotate around y - axis
    var rotatePos = Input.GetAxis ("Horizontal") ? 
                       Input.GetAxis ("Horizontal") : joyStickInput(rotateJoystick);
    transform.Rotate(0, rotatePos * rotateSpeed, 0);
 
    // Move forward / backward
    var forward = transform.TransformDirection(Vector3.forward);
    var movePos = Input.GetAxis ("Vertical") ? 
                     Input.GetAxis ("Vertical") : joyStickInput(moveJoystick);
    var curSpeed = speed * movePos;
    controller.SimpleMove(forward * curSpeed);
  }
 function joyStickInput (joystick : Joystick) {
    var absJoyPos = Vector2 (Mathf.Abs(joystick.position.x),
                                   Mathf.Abs(joystick.position.y));
    var xDirection = (joystick.position.x > 0) ? 1 : -1;
    var yDirection = (joystick.position.y > 0) ? 1 : -1;
    return ( ( absJoyPos.x > absJoyPos.y) ? absJoyPos.x * xDirection : absJoyPos.y * yDirection);
}
function OnCollisionStay ()
{
    grounded = true;    
}
function OnGUI(){
	if(GUI.Button(Rect(Screen.width /2.7 + 0,Screen.height /1 - 100,500,100), "Jump")){

		
	}
}
@script RequireComponent(CharacterController)

I cannot seem to make the character jump by adding code to function OnGUI(){}.

You OnGUI code is listening for a button press, but it does absolutely nothing when the button is actually pressed!

You will need something like this:

function OnGUI(){
    if(GUI.Button(Rect(Screen.width /2.7 + 0,Screen.height /1 - 100,500,100), "Jump")){
 
         Jump();
 
    }
}

function Jump(){
 // jump code here...
}