Question about distance between 2 objects

Unity Engine
1

This is pretty much newbie question.

I am measuring the distance between two objects with the script below. Anyway, how can I measure the distance only in the x and z axis? Basically, I would like to omit the altitude of objects when measuring the distance between them. Is there any simple way to do this?

var distance: float;
var A : GameObject;
var B : GameObject;

function Update () {

// calculate distance between A and B
	
distance = Vector3.Distance(A.transform.position, B.transform.position);
		
}
2 
Vector3 p1 = A.transform.position;
Vector3 p2 = B.transform.position;
p1.y = p2.y;

distance = (p1-p2).magnitude;
3

Thanks for offering to help me menneske! Anyway, I ran to some problems when testing the script. Below is the script like I have it right now. Do you have idea what is causing the problem?

According to Unity:
Assets/Scripts/NewBehaviourScript.js(9,8 ): UCE0001: ‘;’ expected. Insert a semicolon at the end.

I inserted the semicolons but then Unity claims:
Assets/Scripts/NewBehaviourScript.js(9,1): BCE0034: Expressions in statements must only be executed for their side-effects.

var distance: float; 
var A : GameObject; 
var B : GameObject; 

function Update () { 

// calculate distance between A and B 
    
Vector3 p1 = A.transform.position; 
Vector3 p2 = B.transform.position; 
p1.y = p2.y; 

distance = (p1-p2).magnitude;
       
}
4

Yeah, sorry, the code I posted is C#, not JavaScript. The javascript would look like this:

var p1 : Vector3 = A.transform.position; 
var p2 : Vector3 = B.transform.position; 
p1.y = p2.y; 

distance = (p1-p2).magnitude;
5

Thanks again!