Help to understand code line

programming flash
1

Hi! I’m reading someone else code, and there is:

j = polygonUtils.clipPolygonStep2(viewport)
            
                    // If the line is visible, then store the computed point(s), and jump to the basic turning point test.
                    if(j & 1) {
                        if (j & 2) {
                            out[out.length] = polygonUtils.Cp_start;

j & 1??
j & 2??

How that works? Integers are not bools, what are they for here? 0_0