AS3 which item in an array has the lower value? - actionscript-3

Question

I’m trying to make a game like tower defence in AS3 and currently cant find solution to check which item in an array has the lower value of distance between enemy and turret, in order to choose which enemy to attack first.
I'm really stuck with this problem and asking for your help.
Here is a short code:
var enemyArray:Array = new Array();
var turretArray:Array = new Array();
addEventListener(Event.EnterFrame, loop);
// adding enemies
for(var i:int=0; i<3; i++){
var enemy:Enemy = new Enemy();
...
...
enemyArray.push(enemy);
addChild(enemy);
}
// adding turret
for(var t:int=0; t<2; t++){
var turret:Turret = new Turret();
...
...
turret.destinationX = 0;
turret.destinationY = 0;
turret.distance = 0;
turretArray.push(turret);
addChild(turret);
}
// loop
function loop(event:Event):void{
for(var j:int=enemyArray.length-1; j>=0; j--){
for(var k:int=turretArray.length-1; k>=0; k--){
// getting destination
turretArray[k].destinationX = turretArray[k].x - enemyArray[j].x;
turretArray[k].destinationY = turretArray[k].y - enemyArray[j].y;
// getting distance between turret and enemy
turretArray[k].distance = Math.sqrt(turretArray[k].destinationX*turretArray[k].destinationX+turretArray[k].destinationY*turretArray[k].destinationY);
// here i need to get min value from all turrets distance
}
}
}

Answer 1

Looks like you just need to be keeping track of the lowest value you've found as you go rather than overwriting it every time (if I've understood your code, correctly).
// loop
function loop(event:Event):void{
for(var k:int=turretArray.length-1; k>=0; k--)
{
turretArray[k].distance = -1;
for(var j:int=enemyArray.length-1; j>=0; j--)
{
var dx = turretArray[k].x - enemyArray[j].x;
var dy = turretArray[k].y - enemyArray[j].y;
var dist = Math.sqrt(dx * dx + dy * dy);
if(dist < turretArray[k].distance || turretArray[k].distance < 0)
{
turretArray[k].distance = dist;
turretArray[k].destinationX = dx;
turretArray[k].destinationY = dy;
}
}
}
}
Here, we store the initial distance value found in turretArray[k].distance, and only overwrite that if we find a lower one. We set it to -1 each time so we can tell if it's been set, yet, or not.

Answer 2

This is the equation you want:
http://www.mathopenref.com/coorddist.html
sqrt( (turret1X - turret2x)^2 + (turret1Y - turret2Y)^2 )