以下是我的代码我试图在前端验证IP地址，但不知何故，这个正则表达式无法正常工作 -
var patt = /[0-255]\.[0-255]\.[0-255]\.[0-255]/;
var str = "90.89.99.90";
if(str.match(patt))
console.log("Valid IP");
else
console.log("Invalid IP");
应输出 - 有效IP
虽然这些IP应该返回 - 无效的IP
＆＃34; fd.45.67.90＆＃34;，＆＃34; 256.67.67.89＆＃34;，＆＃34; @@。45.67.90＆＃34;等等
让我知道我在使用正则表达式做错了什么。
答案 0 :(得分：4)
正则表达式范围不符合您的想法。 [x-y]范围包含从x到y的ascii中的所有字符。
因此[0-255]匹配0到2（又名0，1和2）和5或简而言之 - [0125]。
要匹配0到255之间的数字，您可以执行以下操作：
\d\d?|1\d\d|2([0-4]\d|5[0-5])
这个想法：
\d\d? - 一位或两位数字1\d\d - 从100到199 2[0-4]\d - 从200到249的数字。25[0-5] - 从250到255 要匹配整个IP，您可以这样做：
^((\d\d?|1\d\d|2([0-4]\d|5[0-5]))\.){3}(\d\d?|1\d\d|2([0-4]\d|5[0-5]))$
答案 1 :(得分：3)
[...]表示＆＃34;字符类＆＃34;意思是它列出了应该匹配的字符;它匹配您列出的任何单个字符。所以你的正则表达式是检查每个段的单个字符，它是0,1,2或5中的任何一个（0-2给我们0,1和2;然后5给我们5 ，第二个被忽略了）。它应检查数字（\d）及其中的1-3（{1,3}）：
var patt = /\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/;
您可能还需要^（输入开始）和$（输入结束），以便foo123.123.123.123bar不匹配：
var patt = /^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/$;
当然，这不足以检查IP 有效。它只是检查有预期的数字;它会很高兴地称891.262.999.42有效。
如果要正确验证它（例如，数字在有效范围内，过滤掉无效的段组合等），您可以提取this comprehensive URL validation regex的IP部分（因为URL可以包含IP）地址，它涵盖了）。值得庆幸的是，迭戈和其他作者很好地评论了它，清楚地确定哪些位做了什么：
//
// Regular Expression for URL validation
//
// Author: Diego Perini
// Updated: 2010/12/05
// License: MIT
//
// Copyright (c) 2010-2013 Diego Perini (http://www.iport.it)
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
//
// the regular expression composed & commented
// could be easily tweaked for RFC compliance,
// it was expressly modified to fit & satisfy
// these test for an URL shortener:
//
// http://mathiasbynens.be/demo/url-regex
//
// Notes on possible differences from a standard/generic validation:
//
// - utf-8 char class take in consideration the full Unicode range
// - TLDs have been made mandatory so single names like "localhost" fails
// - protocols have been restricted to ftp, http and https only as requested
//
// Changes:
//
// - IP address dotted notation validation, range: 1.0.0.0 - 223.255.255.255
// first and last IP address of each class is considered invalid
// (since they are broadcast/network addresses)
//
// - Added exclusion of private, reserved and/or local networks ranges
//
// - Made starting path slash optional (http://example.com?foo=bar)
//
// - Allow a dot (.) at the end of hostnames (http://example.com.)
//
// Compressed one-line versions:
//
// Javascript version
//
// /^(?:(?:https?|ftp):\/\/)(?:\S+(?::\S*)?@)?(?:(?!(?:10|127)(?:\.\d{1,3}){3})(?!(?:169\.254|192\.168)(?:\.\d{1,3}){2})(?!172\.(?:1[6-9]|2\d|3[0-1])(?:\.\d{1,3}){2})(?:[1-9]\d?|1\d\d|2[01]\d|22[0-3])(?:\.(?:1?\d{1,2}|2[0-4]\d|25[0-5])){2}(?:\.(?:[1-9]\d?|1\d\d|2[0-4]\d|25[0-4]))|(?:(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)(?:\.(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)*(?:\.(?:[a-z\u00a1-\uffff]{2,}))\.?)(?::\d{2,5})?(?:[/?#]\S*)?$/i
//
// PHP version
//
// _^(?:(?:https?|ftp)://)(?:\S+(?::\S*)?@)?(?:(?!(?:10|127)(?:\.\d{1,3}){3})(?!(?:169\.254|192\.168)(?:\.\d{1,3}){2})(?!172\.(?:1[6-9]|2\d|3[0-1])(?:\.\d{1,3}){2})(?:[1-9]\d?|1\d\d|2[01]\d|22[0-3])(?:\.(?:1?\d{1,2}|2[0-4]\d|25[0-5])){2}(?:\.(?:[1-9]\d?|1\d\d|2[0-4]\d|25[0-4]))|(?:(?:[a-z\x{00a1}-\x{ffff}0-9]-*)*[a-z\x{00a1}-\x{ffff}0-9]+)(?:\.(?:[a-z\x{00a1}-\x{ffff}0-9]-*)*[a-z\x{00a1}-\x{ffff}0-9]+)*(?:\.(?:[a-z\x{00a1}-\x{ffff}]{2,}))\.?)(?::\d{2,5})?(?:[/?#]\S*)?$_iuS
//
var re_weburl = new RegExp(
"^" +
// protocol identifier
"(?:(?:https?|ftp)://)" +
// user:pass authentication
"(?:\\S+(?::\\S*)?@)?" +
"(?:" +
// IP address exclusion
// private & local networks
"(?!(?:10|127)(?:\\.\\d{1,3}){3})" +
"(?!(?:169\\.254|192\\.168)(?:\\.\\d{1,3}){2})" +
"(?!172\\.(?:1[6-9]|2\\d|3[0-1])(?:\\.\\d{1,3}){2})" +
// IP address dotted notation octets
// excludes loopback network 0.0.0.0
// excludes reserved space >= 224.0.0.0
// excludes network & broacast addresses
// (first & last IP address of each class)
"(?:[1-9]\\d?|1\\d\\d|2[01]\\d|22[0-3])" +
"(?:\\.(?:1?\\d{1,2}|2[0-4]\\d|25[0-5])){2}" +
"(?:\\.(?:[1-9]\\d?|1\\d\\d|2[0-4]\\d|25[0-4]))" +
"|" +
// host name
"(?:(?:[a-z\\u00a1-\\uffff0-9]-*)*[a-z\\u00a1-\\uffff0-9]+)" +
// domain name
"(?:\\.(?:[a-z\\u00a1-\\uffff0-9]-*)*[a-z\\u00a1-\\uffff0-9]+)*" +
// TLD identifier
"(?:\\.(?:[a-z\\u00a1-\\uffff]{2,}))" +
// TLD may end with dot
"\\.?" +
")" +
// port number
"(?::\\d{2,5})?" +
// resource path
"(?:[/?#]\\S*)?" +
"$", "i"
);
答案 2 :(得分：1)
这是一个正则表达式变体（基于ndn＆＃39; s answer above），它将检查整个输入文本是否为有效的IP：
^(?:(?:\d{1,2}|1\d{2}|2(?:[0-4]\d|5[0-5]))\.){3}(?:\d{1,2}|1\d{2}|2(?:[0-4]\d|5[0-5]))$
请参阅regex demo
以下是一个解决方案，可用于从较大的文本中提取有效的IP：
\b(?:(?:\d{1,2}|1\d{2}|2(?:[0-4]\d|5[0-5]))\.){3}(?:\d{1,2}|1\d{2}|2(?:[0-4]\d|5[0-5]))\b
请参阅another demo
解释：
^ - 字符串的开头（如果您不需要在字符串的开头匹配，请替换为\b字边界）(?:(?:\d{1,2}|1\d{2}|2(?:[0-4]\d|5[0-5]))\.){3} - 3次出现
(?:\d{1,2}|1\d{2}|2(?:[0-4]\d|5[0-5])) - 1位或2位数字序列，或1xx数字（1\d{2}）或200-255范围内的整数范围（感谢{{ 1}}）2(?:[0-4]\d|5[0-5]) - 文字句号\. - 见上文（只是IP地址的最后一部分）(?:\d{1,2}|1\d{2}|2(?:[0-4]\d|5[0-5])) - 字符串结尾（如果您只需要一个完整的单词匹配，请替换为$。）注意：在JS中，您可以使用文字表示法来声明这些正则表达式，例如：
\b