script.js

const imageContainer = document.getElementById('image-container');
const loader = document.getElementById('loader');

// We are using a let instead of a const because the value within our photosArray will change everytime we make a request 
let photosArray = [];
let ready = false;
let imagesLoaded = 0;
let totalImages = 0;
let isInitialLoad = true;

// Unsplash API
let initialLoad = 5; 
const apiKey = 'QT2BjdLuxwXMcYHMRSDO7sMymkAq3L8Z5-yb6_ju6iM';
let apiUrl = `https://api.unsplash.com/photos/random/?client_id=${apiKey}&count=${initialLoad}`;

function updateAPIUrl(imgLoadCount){
    apiUrl = `https://api.unsplash.com/photos/random/?client_id=${apiKey}&count=${imgLoadCount}`;
}

// Check if pictures loaded is the first load or not, if not set initialLoad to 30
function moreImageLoad(initialLoadCount) {
    imagesLoaded++;
    if(imagesLoaded === totalImages) {
        ready = true;
        loader.hidden = true;
    }
}

// Check if all images were loaded
function imageLoaded() {
    moreImageLoad();
    apiUrl = `https://api.unsplash.com/photos/random/?client_id=${apiKey}&count=${initialLoad}`;
}

// Helper Function to set attributes on DOM Elements
function setAttributes(element, attributes) {
    for(const key in attributes) {
        element.setAttribute(key, attributes[key]);
    }
}

// Create Elemnts for Links and Photos, Add to DOM
function displayPhotos() {
    imagesLoaded = 0;
    totalImages = photosArray.length;
    // Run function for each object in phototsArray
    photosArray.forEach((photo) => {
        // Create <a> to link to unsplash 
        const item = document.createElement('a');
        setAttributes(item, {
            href: photo.links.html,
            target: '_blank',
        });

        // Create <img> for photo
        const img= document.createElement('img');
        setAttributes(img, {
            src: photo.urls.regular,
            alt: photo.alt_description,
            title: photo.alt_description,
        });

        // Event Listener, check when each is finished loading
        img.addEventListener('load', imageLoaded);

        // Put <img> inside <a>, then put both inside imageContainer Element
        item.appendChild(img);
        imageContainer.appendChild(item);
    });
}

// Get photos from Unsplash API
async function getPhotos() {
    try {
        const response = await fetch(apiUrl);
        photosArray = await response.json();
        displayPhotos();
        if(isInitialLoad){
            updateAPIUrl(30);
            isInitialLoad = false;
        }
    } catch(error) {
        // Catch error here
    }
}

// Check to see if scrolling near bottom of page, load more photos
window.addEventListener('scroll', () => {
    if(window.innerHeight + window.scrollY >= document.body.offsetHeight - 1000 && ready){
        ready = false;
        getPhotos();
    }
});

// On Load 
getPhotos();