求一JS验证方法

function url_exists($url) {
    // Version 4.x supported
    $handle  = curl_init($url);
    if (false === $handle)
    {
        return false;
    }
    curl_setopt($handle, CURLOPT_HEADER, false);
    curl_setopt($handle, CURLOPT_FAILONERROR, true);  // this works
    curl_setopt($handle, CURLOPT_HTTPHEADER, Array("User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.15) Gecko/20080623 Firefox/2.0.0.15") ); // request as if Firefox
    curl_setopt($handle, CURLOPT_NOBODY, true);
    curl_setopt($handle, CURLOPT_RETURNTRANSFER, false);
    $connectable = curl_exec($handle);
    curl_close($handle);
    return $connectable;
}

$uri='XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX;
var_dump(url_exists($uri)); //true

$uri='XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX;
var_dump(url_exists($uri)); //false

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