正則表達式驗證密碼 - Codewars

Question

免責聲明：這是一個Codewars問題。

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.

到目前爲止，這是我的嘗試：

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

這樣做有什麼到目前爲止是確保每個字符是字母數字，該密碼至少有6個字符。它似乎在這些方面正常工作。

我卡在部分地方需要一個有效的密碼至少有一個小寫字母，一個大寫字母和一個數字。我如何使用單個正則表達式來表達這些要求以及以前的要求？

我可以很容易地做到這一點在JavaScript，但我希望做它通過一個正則表達式單單因爲這是問題是什麼測試。

Answer 1

您需要使用向前看符號：

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

說明：

^    # 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