有人提到了 Jquery Validation 插件，如果你只是想验证 url 似乎有点矫枉过正，这里是插件中的正则表达式行:

Someone mentioned the Jquery Validation plugin, seems overkill if you just want to validate the url, here is the line of regex from the plugin:

return this.optional(element) || /^(https?|ftp)://(((([a-z]|d|-|.|_|~|[u00A0-uD7FFuF900-uFDCFuFDF0-uFFEF])|(%[da-f]{2})|[!$&'()*+,;=]|:)*@)?(((d|[1-9]d|1dd|2[0-4]d|25[0-5]).(d|[1-9]d|1dd|2[0-4]d|25[0-5]).(d|[1-9]d|1dd|2[0-4]d|25[0-5]).(d|[1-9]d|1dd|2[0-4]d|25[0-5]))|((([a-z]|d|[u00A0-uD7FFuF900-uFDCFuFDF0-uFFEF])|(([a-z]|d|[u00A0-uD7FFuF900-uFDCFuFDF0-uFFEF])([a-z]|d|-|.|_|~|[u00A0-uD7FFuF900-uFDCFuFDF0-uFFEF])*([a-z]|d|[u00A0-uD7FFuF900-uFDCFuFDF0-uFFEF]))).)+(([a-z]|[u00A0-uD7FFuF900-uFDCFuFDF0-uFFEF])|(([a-z]|[u00A0-uD7FFuF900-uFDCFuFDF0-uFFEF])([a-z]|d|-|.|_|~|[u00A0-uD7FFuF900-uFDCFuFDF0-uFFEF])*([a-z]|[u00A0-uD7FFuF900-uFDCFuFDF0-uFFEF]))).?)(:d*)?)(/((([a-z]|d|-|.|_|~|[u00A0-uD7FFuF900-uFDCFuFDF0-uFFEF])|(%[da-f]{2})|[!$&'()*+,;=]|:|@)+(/(([a-z]|d|-|.|_|~|[u00A0-uD7FFuF900-uFDCFuFDF0-uFFEF])|(%[da-f]{2})|[!$&'()*+,;=]|:|@)*)*)?)?(?((([a-z]|d|-|.|_|~|[u00A0-uD7FFuF900-uFDCFuFDF0-uFFEF])|(%[da-f]{2})|[!$&'()*+,;=]|:|@)|[uE000-uF8FF]|/|?)*)?(#((([a-z]|d|-|.|_|~|[u00A0-uD7FFuF900-uFDCFuFDF0-uFFEF])|(%[da-f]{2})|[!$&'()*+,;=]|:|@)|/|?)*)?$/i.test(value);

这是他们的来源:http://projects.scottsplayground.com/iri/

@nhahtdh 指出这已更新为:

Pointed out by @nhahtdh This has been updated to:

        // Copyright (c) 2010-2013 Diego Perini, MIT licensed
        // https://gist.github.com/dperini/729294
        // see also https://mathiasbynens.be/demo/url-regex
        // modified to allow protocol-relative URLs
        return this.optional( element ) || /^(?:(?:(?:https?|ftp):)?//)(?:S+(?::S*)?@)?(?:(?!(?:10|127)(?:.d{1,3}){3})(?!(?:169.254|192.168)(?:.d{1,3}){2})(?!172.(?:1[6-9]|2d|3[0-1])(?:.d{1,3}){2})(?:[1-9]d?|1dd|2[01]d|22[0-3])(?:.(?:1?d{1,2}|2[0-4]d|25[0-5])){2}(?:.(?:[1-9]d?|1dd|2[0-4]d|25[0-4]))|(?:(?:[a-zu00a1-uffff0-9]-*)*[a-zu00a1-uffff0-9]+)(?:.(?:[a-zu00a1-uffff0-9]-*)*[a-zu00a1-uffff0-9]+)*(?:.(?:[a-zu00a1-uffff]{2,})).?)(?::d{2,5})?(?:[/?#]S*)?$/i.test( value );

来源:https://github.com/jzaefferer/jquery-validation/blob/c1db10a34c0847c28a5bd30e3ee1117e137ca834/src/core.js#L1349