This JavaScript class converts equatorial coordinates (Right ascension and Declination) into horizontal coordinates (Altitude and Azimuth).
npm i radectoaltaz
In order to use it, import the RaDecToAltAz.js file first and then call the class. Variables alt and az are the corresponding values for altitude and azimuth.
let radectoaltaz = require('radectoaltaz');
let ra = 23.45; //hours
let dec = 16.6; //degrees
let lat = 1.4; //degrees
let lng = 34.1; //degrees
let coordinates = new radectoaltaz(ra,dec,lat,lng);
let alt = coordinates.getAlt();
let az = coordinates.getAz();
console.log(alt,az);