如何将变量与IPv4正则表达式正确匹配 [英] How to correctly match a variable against an IPv4 regex

问题描述

我是JavaScript的新手，正在尝试创建一个简单的函数来检查变量是否为有效的IPv4地址.

I'm new to JavaScript and am trying to create a simple function checking whether a variable is a valid IPv4 address, or not.

当前，我正在使用在线工具尝试代码.

Currently, I'm just trying the code with an online tool.

我从stackexchange复制了正则表达式，并试图将其与硬编码变量匹配，但是在线编辑器声称它是无效的JavaScript代码.

I copied the regex from stackexchange and tried to match it against a hardcoded variable, but the online editor claims it's invalid JavaScript code.

ip='127.0.0.1';

if (ip.match(^([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])\\.([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])\\.([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])\\.([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])$){
    alert('IPv4');
}
else{
    alert('no IPv4');
}

如何正确检查静态变量是否是带有正则表达式的有效IPv4地址?

How do I correctly check if a static variable is a valid IPv4 address with a regex?

推荐答案

您必须使用定界符将正则表达式括起来:

You have to surround the regex with delimiter:

if (ip.match(/^([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])\.([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])\.([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])\.([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])$/)){
//    here __^                                                                                                                                                     and here __^

您可以使用量词来减少正则表达式的长度:

You could use a quantifier to reduce the length of regex:

if (ip.match(/^([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])(\.[01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5]){3}$/)) {

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