weather.service.js

'use strict'
const BASE_URL = 'https://api.openweathermap.org/data/2.5/onecall'
const API_KEY = '81b29166d4b3448f6540eab75f83777c'
const DEFAULT_OPTIONS = {
    coord: { lon: -75.76, lat: 45.35 }, // Algonquin College
    units: 'metric'
}
const cache = new Map()

/**
 * @typedef {Object} APIOptions
 * @property {string} units [metric, imperial, standard]
 * @property {Object} coord Location coordinates
 * @property {number} coord.lon Longitude
 * @property {number} coord.lat Latitude
 */

/**
 * Get the latest weather forecast for the given location.
 * Results are cached for 10 minutes.
 * @param {APIOptions} options
 * @returns {Object} Forecast results
 * @see https://openweathermap.org/api/one-call-api#data
 */
export async function getForecast(options) {
    const { coord, units } = Object.assign({}, DEFAULT_OPTIONS, options)
    const cacheItem = cache.get(coord)
    if (cacheItem && !isExpired(cacheItem.current.dt)) {
        return cacheItem
    }
    const forecast = await fetchForecast({ units, coord })
    cache.set(coord, forecast)
    return forecast

    /**
     * Helper function to check cache expiry
     * @param {number} cacheTime UNIX timestamp in seconds
     */
    function isExpired(cacheTime) {
        const TEN_MINUTES = 600 // seconds
        const currentTime = Math.floor(Date.now() / 1000) // convert from ms to s
        const elapsedTime = currentTime - cacheTime
        return elapsedTime > TEN_MINUTES
    }
}

/**
 * Private function to make the actual `fetch()` call to the API
 * @param {APIOptions} options
 */
async function fetchForecast({ coord: { lat, lon }, units }) {
    const url = `${BASE_URL}?lat=${lat}&lon=${lon}&units=${units}&appid=${API_KEY}`
    const response = await fetch(url)
    if (!response.ok) throw new Error(response.statusText)
    return response.json()
}

/**
 * Returns an <img> HTMLElement with the correct URL to display
 * the OpenWeather image corresponding to the given `iconCode`.
 * @param {string} iconCode
 */
export function createWeatherIcon(iconCode) {
    let img = document.createElement('img')
    img.setAttribute(
        'src',
        'https://openweathermap.org/img/wn/' + iconCode + '@4x.png'
    )
    img.setAttribute('alt', '')
    return img
}