Find Closest Object

//Actor structure
function Actor( posx, posy){
    this.posx = posx;
    this.posy = posy;
}

//calc abs from a to b
function dist(a,  b){return Math.abs(b-a);}


//finds nearest entity and return it ID
function findNearest(MainActor){
    var nearest = 0;
    if(ActorList[0].posx === MainActor.posx && ActorList[0].posy === MainActor.posy){
        var minDistX = dist(MainActor.posx,ActorList[1].posx);
        var minDistY = dist(MainActor.posy,ActorList[1].posy);
        var minDist = dist(minDistX,minDistY);
        } else {
        var minDistX = dist(MainActor.posx,ActorList[0].posx);
        var minDistY = dist(MainActor.posy,ActorList[0].posy);
        var minDist = dist(minDistX,minDistY);
    }
    for(var i = 0; i < ActorList.length; i++){
        if(ActorList[i].posx === MainActor.posx && ActorList[i].posy === MainActor.posy) continue;
        else{

            minDistX = dist(MainActor.posx,ActorList[i].posx);
            minDistY = dist(MainActor.posy,ActorList[i].posy);
            if(dist(minDistX,minDistY)<minDist){
                minDist = dist(minDistX,minDistY);
                nearest = i;
            }
        }
    }
    return nearest;
}