检查JavaScript字符串是否是URL

在JavaScript中是否有一种方法来检查字符串是否是URL?

regex被排除在外，因为URL很可能写成stackoverflow;也就是说，它可能没有。com, WWW或http。

当前回答

我建议使用锚元素，而不是使用正则表达式。

当你设置一个锚的href属性时，其他各种属性也会被设置。

var parser = document.createElement('a');
parser.href = "http://example.com:3000/pathname/?search=test#hash";

parser.protocol; // => "http:"
parser.hostname; // => "example.com"
parser.port;     // => "3000"
parser.pathname; // => "/pathname/"
parser.search;   // => "?search=test"
parser.hash;     // => "#hash"
parser.host;     // => "example.com:3000"

源

但是，如果href绑定的值不是一个有效的url，那么这些辅助属性的值将是空字符串。

编辑:正如评论中指出的:如果使用了无效的url，则可以替换当前url的属性。

所以，只要你没有传递当前页面的URL，你可以这样做:

function isValidURL(str) {
   var a  = document.createElement('a');
   a.href = str;
   return (a.host && a.host != window.location.host);
}

2016-01-09 15:00:57

其他回答

如果你也需要支持https://localhost:3000，那么使用[Devshed]s regex的修改版本。

    function isURL(url) {
        if(!url) return false;
        var 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
            'localhost' + // OR localhost
            '(\\:\\d+)?(\\/[-a-z\\d%_.~+]*)*'+ // port and path
            '(\\?[;&a-z\\d%_.~+=-]*)?'+ // query string
            '(\\#[-a-z\\d_]*)?$', 'i'); // fragment locator
        return pattern.test(url);
    }

2020-01-13 23:08:12

对已接受答案的改进…

Check for ftp/ftps as protocol Has double escaping for backslashes (\\) Ensures that domains have a dot and an extension (.com .io .xyz) Allows full colon (:) in the path e.g. http://thingiverse.com/download:1894343 Allows ampersand (&) in path e.g http://en.wikipedia.org/wiki/Procter_&_Gamble Allows @ symbol in path e.g. https://medium.com/@techytimo isURL(str) { var pattern = new RegExp('^((ft|htt)ps?:\\/\\/)?'+ // protocol '((([a-z\\d]([a-z\\d-]*[a-z\\d])*)\\.)+[a-z]{2,}|'+ // domain name and extension '((\\d{1,3}\\.){3}\\d{1,3}))'+ // OR ip (v4) address '(\\:\\d+)?'+ // port '(\\/[-a-z\\d%@_.~+&:]*)*'+ // path '(\\?[;&a-z\\d%@_.,~+&:=-]*)?'+ // query string '(\\#[-a-z\\d_]*)?$','i'); // fragment locator return pattern.test(str); }

2017-08-08 11:55:55

使用纯正则表达式很难做到这一点，因为url有很多“不方便”的地方。

For example domain names have complicated restrictions on hyphens: a. It is allowed to have many consecutive hyphens in the middle. b. but the first character and last character of the domain name cannot be a hyphen c. The 3rd and 4th character cannot be both hyphen Similarly port number can only be in the range 1-65535. This is easy to check if you extract the port part and convert to int but quite difficult to check with a regular expression. There is also no easy way to check valid domain extensions. Some countries have second-level domains(such as 'co.uk'), or the extension can be a long word such as '.international'. And new TLDs are added regularly. This type of things can only be checked against a hard-coded list. (see https://en.wikipedia.org/wiki/Top-level_domain) Then there are magnet urls, ftp addresses etc. These all have different requirements.

然而，这里有一个函数可以处理几乎所有的事情，除了:

案例1。c 接受任何1-5位数的端口号接受任何扩展2-13个字符不接受ftp，磁铁等…

2019-02-10 19:51:48

这里只是一个非常简单的检查，以确保有一个有效的协议，并且域扩展名必须是两个或更多字符。

is_valid_url = ( $url ) => {

    let $url_object = null;

    try {
        $url_object = new URL( $url );
    } catch ( $error ) {
        return false;
    }

    const $protocol = $url_object.protocol;
    const $protocol_position = $url.lastIndexOf( $protocol );
    const $domain_extension_position = $url.lastIndexOf( '.' );

    return (
        $protocol_position === 0 &&
        [ 'http:', 'https:' ].indexOf( $protocol ) !== - 1 &&
        $domain_extension_position > 2 && $url.length - $domain_extension_position > 2
    );

};

2019-04-02 15:01:59

Mathias Bynens编译了一个带有测试URL的知名URL正则表达式列表。没有什么理由去写一个新的正则表达式;只要选择一个现有的最适合你的。

但是这些正则表达式的比较表也表明，使用单个正则表达式进行URL验证几乎是不可能的。Bynens列出的所有正则表达式都会产生假阳性和假阴性。

我建议您使用现有的URL解析器(例如JavaScript中的新URL('http://www.example.com/'))，然后应用您想要对URL响应的解析和规范化形式执行的检查。它的组件。使用JavaScript URL接口还有一个额外的好处，它只接受浏览器真正接受的URL。

您还应该记住，技术上不正确的url仍然可以工作。例如http://w_w_w.example.com/， http://www..example.com/， http://123.example.com/都有一个无效的主机名部分，但我知道的每个浏览器都会试图打开它们而没有抱怨，当你在/etc/hosts/中为这些无效的名称指定IP地址时，这样的url甚至可以工作，但只在你的计算机上。

因此，问题不在于URL是否有效，而在于在特定的上下文中应该允许哪些URL工作。

如果你想进行URL验证，有很多细节和边缘情况很容易被忽视:

URLs may contain credentials as in http://user:password@www.example.com/. Port numbers must be in the range of 0-65535, but you may still want to exclude the wildcard port 0. Port numbers may have leading zeros as in http://www.example.com:000080/. IPv4 addresses are by no means restricted to 4 decimal integers in the range of 0-255. You can use one to four integers, and they can be decimal, octal or hexadecimal. The URLs https://010.010.000010.010/, https://0x8.0x8.0x0008.0x8/, https://8.8.2056/, https://8.526344/, https://134744072/ are all valid and just creative ways of writing https://8.8.8.8/. Allowing loopback addresses (http://127.0.0.1/), private IP addresses (http://192.168.1.1), link-local addresses (http://169.254.100.200) and so on may have an impact on security or privacy. If, for instance, you allow them as the address of user avatars in a forum, you cause the users' browsers to send unsolicited network requests in their local network and in the internet of things such requests may cause funny and not so funny things to happen in your home. For the same reasons, you may want to discard links to not fully qualified hostnames, in other words hostnames without a dot. But hostnames may always have a trailing dot (like in http://www.stackoverflow.com.). The hostname portion of a link may contain angle brackets for IPv6 addresses as in http://[::1]. IPv6 addresses also have ranges for private networks or link-local addresses etc. If you block certain IPv4 addresses, keep in mind that for example https://127.0.0.1 and https://[::ffff:127.0.0.1] point to the same resource (if the loopback device of your machine is IPv6 ready). The hostname portion of URLs may now contain Unicode, so that the character range [-0-9a-zA-z] is definitely no longer sufficient. Many registries for top-level domains define specific restrictions, for example on the allowed set of Unicode characters. Or they subdivide their namespace (like co.uk and many others). Top-level domains must not contain decimal digits, and the hyphen is not allowed unless for the IDN A-label prefix "xn--". Unicode top-level domains (and their punycode encoding with "xn--") must still contain only letters but who wants to check that in a regex?

应用哪些限制和规则取决于项目需求和喜好。

我最近为一个web应用程序编写了一个URL验证器，它适用于论坛、社交网络等用户提供的URL。你可以把它作为你自己的基础:

(Angular)前端的JavaScript/Typescript版本 Perl版本的后端

我还写了一篇博客文章《URL验证的血淋淋的细节》，提供了更深入的信息。

2020-01-17 09:51:56

检查JavaScript字符串是否是URL

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