Download

You must have cty.dat downloaded from officially maintained site

Download it here http://www.country-files.com/bigcty/cty.dat

Usage

(async () => {
    const ad1cCtyImpl = new AD1CCtyImpl();
    try {
        await ad1cCtyImpl.loadCty("cty.dat"); // Replace with your file path
        console.log("Entities:" + ad1cCtyImpl.entities.size);
        console.log("Prefixes:" + ad1cCtyImpl.prefixes.size);
        console.log(ad1cCtyImpl.lookup("LY1H"));
    } catch (error) {
        console.error(error);
    }
})();

Demo