示例 - 正则表达式 - js [英] Example - regular expression - js

问题描述

这是一个（天真）简单的密码检查程序，可以查找3到6个字符和至少一个数字：

Here is a (naively) simple password checker that looks for between 3 and 6 characters and at least one number:

let password = "abc123";
let checkPass = /(?=\w{3,6})(?=\D*\d)/;
checkPass.test(password); // Returns true

我为什么要使用'\D *'？

不能理解这个代码的这个字符的含义..

如果没有这个例子：bana12;



我尝试了什么：



带有此字符的代码，并搜索类似的示例答案。

why should i use the '\D*'?
can't understand the meaning of this character of this code..
with out this it would not work for example of: "bana12";

What I have tried:

code with out this character, and search for similar examples answers.

推荐答案

打开Expresso - 你知道，我建议你为之前的两个问题安装的应用程序。

现在，将正则表达式粘贴到正则表达式窗格中：

Open Expresso - you know, the app I suggested you install for both of your previous questions.
Now, paste the Regex into the "Regular Expression" pane:

(?=\w{3,6})(?=\D*\d)

在Regex Analyzer窗格中查看它是正确的。展开所有分支。

看看它如何解释 \ D * \d 是什么？



但是正则表达式没用。它明确地捕获任何东西，并且如果它确实没有用，因为它试图捕获两个后缀并将它们排除在外......

Look to it's right at the "Regex Analyzer" pane. Expand all branches.
See how it explains what \D*\d does?

But that Regex is useless. It explicitly capture nothing, and wouldn't work if it did since it's trying to capture two suffixes and exclude them both...

引用：

这是一个（天真）简单的密码检查器，可以查找3到6个字符和至少一个数字：

Here is a (naively) simple password checker that looks for between 3 and 6 characters and at least one number:

您滥用RegEx， RegEx用于检查字符串是否与'模式'匹配。

URL，电子邮件地址，十进制数，车牌等都遵循构造规则，模式。

使用 Debuggex 链接查看RegEx的漂亮图表并试验一些候选密码以查看匹配内容和不匹配内容。

这是一个链接RegEx文档：

perlre - perldoc.perl.org [ ^ ]

以下是帮助构建RegEx并调试它们的工具的链接：<无线电通信/>
.NET正则表达式测试程序 - 正则表达式风暴 [ ^ ]

Expresso正则表达式工具 [ ^ ]

< a href =http://regexr.com/> RegExr：Learn，Build，&测试RegEx [ ^ ]

在线正则表达式测试器和调试器：PHP，PCRE，Python，Golang和JavaScript [ ^ ]

这个显示RegEx是一个很好的图表，它非常有助于理解RegEx的作用： Debuggex：在线可视正则表达式测试器。 JavaScript，Python和PCRE。 [ ^ ]

此网站还在一个漂亮的图表中显示正则表达式，但无法测试与RegEx匹配的内容： Regexper [ ^ ]



Nota：RegEx是一个复杂的主题阅读文档是必须掌握的。

You are misusing RegEx, RegEx is used to check if a string match a 'pattern'.
Things like URL, Email address, decimal number, car plates are following rules of construct, the pattern.
Use the Debuggex link to see a nice graph of the RegEx and to experiment with some candidate password to see what match and what don't.
Here is a link to RegEx documentation:
perlre - perldoc.perl.org[^]
Here is links to tools to help build RegEx and debug them:
.NET Regex Tester - Regex Storm[^]
Expresso Regular Expression Tool[^]
RegExr: Learn, Build, & Test RegEx[^]
Online regex tester and debugger: PHP, PCRE, Python, Golang and JavaScript[^]
This one show you the RegEx as a nice graph which is really helpful to understand what is doing a RegEx: Debuggex: Online visual regex tester. JavaScript, Python, and PCRE.[^]
This site also show the Regex in a nice graph but can't test what match the RegEx: Regexper[^]

Nota: RegEx is a sophisticated subject reading documentation is mandatory to master it.

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