#define main

// init code here

p_angle = 0;

#define step

// update code here

#define draw

// draw code here

var numdirs;

var numdirs = 4

var d;

var dd;

d = floor(((p_angle+180/numdirs) mod 360)/(360/numdirs));

dd = round( p_angle*num_dirs/360 );

draw_text(10,10,d);

draw_text(10,30,dd);

p_angle +=5;

Because you've typo-ed "num_dirs" instead of "numdirs" on line assigning "dd".

Since this is JS, unset variable is equal to "undefined", math operations on it result in "NaN", and round(NaN) is... 1? Well.

Facepalm... sorry