正则表达式验证密码 - Codewars

Question

免责声明：这是一个Codewars问题。

You need to write regex that will validate a password to make sure it meets the following criteria:

• At least six characters long
• contains a lowercase letter
• contains an uppercase letter
• contains a number

Valid passwords will only be alphanumeric characters.

到目前为止，这是我的尝试：

function validate(password) { 
    return /^[A-Za-z0-9]{6,}$/.test(password); 
} 

这样做有什么到目前为止是确保每个字符是字母数字，该密码至少有6个字符。它似乎在这些方面正常工作。

我卡在部分地方需要一个有效的密码至少有一个小写字母，一个大写字母和一个数字。我如何使用单个正则表达式来表达这些要求以及以前的要求？

我可以很容易地做到这一点在JavaScript，但我希望做它通过一个正则表达式单单因为这是问题是什么测试。

Answer 1

您需要使用向前看符号：

function validate(password) { 
    return /^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])[A-Za-z0-9]{6,}$/.test(password); 
} 

说明：

^    # start of input 
(?=.*?[A-Z]) # Lookahead to make sure there is at least one upper case letter 
(?=.*?[a-z]) # Lookahead to make sure there is at least one upper case letter 
(?=.*?[0-9]) # Lookahead to make sure there is at least one number 
[A-Za-z0-9]{6,} # Make sure there are at least 6 characters of [A-Za-z0-9] 
$    # end of input