# Sunset / Sunrise dynamic filed

Hello,

Is there any way to add field that will dynamically calculate:

• sunrise time
• sunset time

Based on:

• location
• date

For example there is this library that can do that GitHub - mourner/suncalc: A tiny JavaScript library for calculating sun/moon positions and phases.

Like this?

I havenâ€™t explained my complete plan to not make things complicated.

1. first to get the sunrise time and then in DATAVIEW plugin
2. Then I want to use this time for further calculations
3. Show this calculated field as one of the DATAVIEW fields

So I cannot use your suggestion for this

I was able to make this library work inside a dataviewjs block, but getting the userâ€™s location silently fails.

Below is almost completely just copying the code from the repo youâ€™ve linked and at the very bottom is a little thing to print the different times it gives you as a DV list

The Code
``````/*
SunCalc is a JavaScript library for calculating sun/moon position and light phases.
https://github.com/mourner/suncalc
*/

// shortcuts for easier to read formulas

var PI   = Math.PI,
sin  = Math.sin,
cos  = Math.cos,
tan  = Math.tan,
asin = Math.asin,
atan = Math.atan2,
acos = Math.acos,

// sun calculations are based on http://aa.quae.nl/en/reken/zonpositie.html formulas

// date/time constants and conversions

var dayMs = 1000 * 60 * 60 * 24,
J1970 = 2440588,
J2000 = 2451545;

function toJulian(date) { return date.valueOf() / dayMs - 0.5 + J1970; }
function fromJulian(j)  { return new Date((j + 0.5 - J1970) * dayMs); }

// general calculations for position

var e = rad * 23.4397; // obliquity of the Earth

function rightAscension(l, b) { return atan(sin(l) * cos(e) - tan(b) * sin(e), cos(l)); }
function declination(l, b)    { return asin(sin(b) * cos(e) + cos(b) * sin(e) * sin(l)); }

function azimuth(H, phi, dec)  { return atan(sin(H), cos(H) * sin(phi) - tan(dec) * cos(phi)); }
function altitude(H, phi, dec) { return asin(sin(phi) * sin(dec) + cos(phi) * cos(dec) * cos(H)); }

function siderealTime(d, lw) { return rad * (280.16 + 360.9856235 * d) - lw; }

function astroRefraction(h) {
if (h < 0) // the following formula works for positive altitudes only.
h = 0; // if h = -0.08901179 a div/0 would occur.

// formula 16.4 of "Astronomical Algorithms" 2nd edition by Jean Meeus (Willmann-Bell, Richmond) 1998.
// 1.02 / tan(h + 10.26 / (h + 5.10)) h in degrees, result in arc minutes -> converted to rad:
return 0.0002967 / Math.tan(h + 0.00312536 / (h + 0.08901179));
}

// general sun calculations

function solarMeanAnomaly(d) { return rad * (357.5291 + 0.98560028 * d); }

function eclipticLongitude(M) {

var C = rad * (1.9148 * sin(M) + 0.02 * sin(2 * M) + 0.0003 * sin(3 * M)), // equation of center
P = rad * 102.9372; // perihelion of the Earth

return M + C + P + PI;
}

function sunCoords(d) {

var M = solarMeanAnomaly(d),
L = eclipticLongitude(M);

return {
dec: declination(L, 0),
ra: rightAscension(L, 0)
};
}

var SunCalc = {};

// calculates sun position for a given date and latitude/longitude

SunCalc.getPosition = function (date, lat, lng) {

var lw  = rad * -lng,
d   = toDays(date),

c  = sunCoords(d),
H  = siderealTime(d, lw) - c.ra;

return {
azimuth: azimuth(H, phi, c.dec),
altitude: altitude(H, phi, c.dec)
};
};

// sun times configuration (angle, morning name, evening name)

var times = SunCalc.times = [
[-0.833, 'sunrise',       'sunset'      ],
[  -0.3, 'sunriseEnd',    'sunsetStart' ],
[    -6, 'dawn',          'dusk'        ],
[   -12, 'nauticalDawn',  'nauticalDusk'],
[   -18, 'nightEnd',      'night'       ],
[     6, 'goldenHourEnd', 'goldenHour'  ]
];

// adds a custom time to the times config

SunCalc.addTime = function (angle, riseName, setName) {
times.push([angle, riseName, setName]);
};

// calculations for sun times

var J0 = 0.0009;

function julianCycle(d, lw) { return Math.round(d - J0 - lw / (2 * PI)); }

function approxTransit(Ht, lw, n) { return J0 + (Ht + lw) / (2 * PI) + n; }
function solarTransitJ(ds, M, L)  { return J2000 + ds + 0.0053 * sin(M) - 0.0069 * sin(2 * L); }

function hourAngle(h, phi, d) { return acos((sin(h) - sin(phi) * sin(d)) / (cos(phi) * cos(d))); }
function observerAngle(height) { return -2.076 * Math.sqrt(height) / 60; }

// returns set time for the given sun altitude
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);
}

// calculates sun times for a given date, latitude/longitude, and, optionally,
// the observer height (in meters) relative to the horizon

SunCalc.getTimes = function (date, lat, lng, height) {

height = height || 0;

var lw = rad * -lng,

dh = observerAngle(height),

d = toDays(date),
n = julianCycle(d, lw),
ds = approxTransit(0, lw, n),

M = solarMeanAnomaly(ds),
L = eclipticLongitude(M),
dec = declination(L, 0),

Jnoon = solarTransitJ(ds, M, L),

i, len, time, h0, Jset, Jrise;

var result = {
solarNoon: fromJulian(Jnoon),
};

for (i = 0, len = times.length; i < len; i += 1) {
time = times[i];
h0 = (time[0] + dh) * rad;

Jset = getSetJ(h0, lw, phi, dec, n, M, L);
Jrise = Jnoon - (Jset - Jnoon);

result[time[1]] = fromJulian(Jrise);
result[time[2]] = fromJulian(Jset);
}

return result;
};

// moon calculations, based on http://aa.quae.nl/en/reken/hemelpositie.html formulas

function moonCoords(d) { // geocentric ecliptic coordinates of the moon

var L = rad * (218.316 + 13.176396 * d), // ecliptic longitude
M = rad * (134.963 + 13.064993 * d), // mean anomaly
F = rad * (93.272 + 13.229350 * d),  // mean distance

l  = L + rad * 6.289 * sin(M), // longitude
b  = rad * 5.128 * sin(F),     // latitude
dt = 385001 - 20905 * cos(M);  // distance to the moon in km

return {
ra: rightAscension(l, b),
dec: declination(l, b),
dist: dt
};
}

SunCalc.getMoonPosition = function (date, lat, lng) {

var lw  = rad * -lng,
d   = toDays(date),

c = moonCoords(d),
H = siderealTime(d, lw) - c.ra,
h = altitude(H, phi, c.dec),
// formula 14.1 of "Astronomical Algorithms" 2nd edition by Jean Meeus (Willmann-Bell, Richmond) 1998.
pa = atan(sin(H), tan(phi) * cos(c.dec) - sin(c.dec) * cos(H));

h = h + astroRefraction(h); // altitude correction for refraction

return {
azimuth: azimuth(H, phi, c.dec),
altitude: h,
distance: c.dist,
parallacticAngle: pa
};
};

// calculations for illumination parameters of the moon,
// based on http://idlastro.gsfc.nasa.gov/ftp/pro/astro/mphase.pro formulas and
// Chapter 48 of "Astronomical Algorithms" 2nd edition by Jean Meeus (Willmann-Bell, Richmond) 1998.

SunCalc.getMoonIllumination = function (date) {

var d = toDays(date || new Date()),
s = sunCoords(d),
m = moonCoords(d),

sdist = 149598000, // distance from Earth to Sun in km

phi = acos(sin(s.dec) * sin(m.dec) + cos(s.dec) * cos(m.dec) * cos(s.ra - m.ra)),
inc = atan(sdist * sin(phi), m.dist - sdist * cos(phi)),
angle = atan(cos(s.dec) * sin(s.ra - m.ra), sin(s.dec) * cos(m.dec) -
cos(s.dec) * sin(m.dec) * cos(s.ra - m.ra));

return {
fraction: (1 + cos(inc)) / 2,
phase: 0.5 + 0.5 * inc * (angle < 0 ? -1 : 1) / Math.PI,
angle: angle
};
};

function hoursLater(date, h) {
return new Date(date.valueOf() + h * dayMs / 24);
}

// calculations for moon rise/set times are based on http://www.stargazing.net/kepler/moonrise.html article

SunCalc.getMoonTimes = function (date, lat, lng, inUTC) {
var t = new Date(date);
if (inUTC) t.setUTCHours(0, 0, 0, 0);
else t.setHours(0, 0, 0, 0);

var hc = 0.133 * rad,
h0 = SunCalc.getMoonPosition(t, lat, lng).altitude - hc,
h1, h2, rise, set, a, b, xe, ye, d, roots, x1, x2, dx;

// go in 2-hour chunks, each time seeing if a 3-point quadratic curve crosses zero (which means rise or set)
for (var i = 1; i <= 24; i += 2) {
h1 = SunCalc.getMoonPosition(hoursLater(t, i), lat, lng).altitude - hc;
h2 = SunCalc.getMoonPosition(hoursLater(t, i + 1), lat, lng).altitude - hc;

a = (h0 + h2) / 2 - h1;
b = (h2 - h0) / 2;
xe = -b / (2 * a);
ye = (a * xe + b) * xe + h1;
d = b * b - 4 * a * h1;
roots = 0;

if (d >= 0) {
dx = Math.sqrt(d) / (Math.abs(a) * 2);
x1 = xe - dx;
x2 = xe + dx;
if (Math.abs(x1) <= 1) roots++;
if (Math.abs(x2) <= 1) roots++;
if (x1 < -1) x1 = x2;
}

if (roots === 1) {
if (h0 < 0) rise = i + x1;
else set = i + x1;

} else if (roots === 2) {
rise = i + (ye < 0 ? x2 : x1);
set = i + (ye < 0 ? x1 : x2);
}

if (rise && set) break;

h0 = h2;
}

var result = {};

if (rise) result.rise = hoursLater(t, rise);
if (set) result.set = hoursLater(t, set);

if (!rise && !set) result[ye > 0 ? 'alwaysUp' : 'alwaysDown'] = true;

return result;
};

const londonTimes = SunCalc.getTimes(new Date(), 51.5, -0.1)

dv.list(Array.from(Object.keys(londonTimes
)).map(v => `\${v} => \${londonTimes[v].toString()}`), "Times")

``````
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