js 检查url是否正确

function isValidUrl(url) {
    const pattern = new RegExp('^(https?:\\/\\/)?'+ // protocol
        '((([a-z\\d]([a-z\\d-]*[a-z\\d])*)\\.)+[a-z]{2,}|'+ // domain name
        '((\\d{1,3}\\.){3}\\d{1,3}))'+ // OR ip (v4) address
        '(\\:\\d+)?(\\/[-a-z\\d%_.~+]*)*'+ // port and path
        '(\\?[;&a-z\\d%_.~+=-]*)?'+ // query string
        '(\\#[-a-z\\d_]*)?$','i'); // fragment locator
    return !!pattern.test(url);
}

console.log(isValidUrl("https://www.example.com")); // true
console.log(isValidUrl("invalid-url")); // false

async function checkUrlReachability(url) {
    try {
        const response = await fetch(url, { method: 'HEAD' });
        return response.ok;
    } catch (error) {
        return false;
    }
}

checkUrlReachability("https://www.example.com").then(isReachable => {
    console.log(isReachable); // true or false
});