you can create it very simple
function find_nearest_node()
{
var dist=-1;
var curr_id=0;
var counter=0;
while(counter<numnodes)
{
if(vec_dist(pointarray[counter*7],my.x)<dist||dist<0)//if you use the 7 vars for a node
{
curr_id=counter;
dist=vec_dist(pointarray[counter*7],my.x);
}
counter+=1;
}
return(curr_id);
}