s2maps-gpu/dist/plugins/preload.js

S2 Maps GPU - An open source, high-performance, and GPU-accelerated map engine for rendering large-scale, interactive maps.

// Keep track of the assets that have been preloaded. Sometimes mulitple maps will be loaded in a single page
const preloadedAssets = new Set();
/**
 * Preload the map and associated CSS
 * @param build - the build type
 * @param version - the version
 */
export async function preloadMap(build, version = 'latest') {
    if (build === 'preloaded')
        return;
    const fullVersion = version === 'latest' ? 'latest' : `v${version}`;
    let startPath = `https://opens2.com/s2maps-gpu/${fullVersion}`;
    if (build === 'flat')
        startPath += '-flat';
    const styleUrl = `${startPath}/s2maps-gpu.min.css`;
    const scriptUrl = build === 'flat' ? `${startPath}/s2maps-gpu.flat.js` : `${startPath}/s2maps-gpu.min.js`;
    // handle replaoding the CSS
    if (!preloadedAssets.has(styleUrl)) {
        preloadedAssets.add(styleUrl);
        preloadStyle(styleUrl);
    }
    // handle reloading the script
    if (!preloadedAssets.has(scriptUrl)) {
        preloadedAssets.add(scriptUrl);
        await preloadScript(scriptUrl);
    }
}
/**
 * Preload a script
 * @param url - the url of the script to load
 * @returns a promise that resolves when the script is loaded
 */
export async function preloadScript(url) {
    return await new Promise((resolve, reject) => {
        const script = document.createElement('script');
        script.src = url;
        script.async = true;
        document.head.appendChild(script);
        /** Load the script; resolve the promise when complete */
        script.onload = () => {
            resolve();
        };
        /**
         * Handle errors
         * @param err - the error
         */
        script.onerror = (err) => {
            const errorMessage = typeof err === 'string' ? err : 'Failed to load script';
            console.error(`Error loading s2maps-gpu from ${url}`, errorMessage);
            reject(new Error(`Failed to load script: ${url}`));
        };
    });
}
/**
 * Preload a style. Be sure we haven't already loaded it
 * @param url - the url
 */
export function preloadStyle(url) {
    if (document.querySelector(`link[href="${url}"]`) === null) {
        const link = document.createElement('link');
        link.rel = 'stylesheet';
        link.type = 'text/css';
        link.href = url;
        document.head.appendChild(link);
    }
}