suncalc.js
function getSetJ(h, lw, phi, dec, n, M, L) {

    var w = hourAngle(h, phi, dec),
        a = approxTransit(w, lw, n);
    return solarTransitJ(a, M, L);
}
function getSetJ(h, lw, phi, dec, n, M, L) {

    var w = hourAngle(h, phi, dec),
        a = approxTransit(w, lw, n);
    return solarTransitJ(a, M, L);
}
function getSetJ ( h , lw , phi , dec , n , M , L ) { var w = hourAngle ( h , phi , dec ) , a = approxTransit ( w , lw , n ) ; return solarTransitJ ( a , M , L ) ; }
returns set time for the given sun altitude
returns set time for the given sun altitude