正则表达式的密码：QUOT; ATLEAST 1个字母，1个数字，特殊字符，不应以特殊字符＆QUOT启动;

问题描述

我需要一个密码字段经常EX pression。

的要求是：

1. 密码长度必须在8到20个字符




2. 必须至少包含一个字母和一个号码并从 特殊字符！@＃$％^＆放; *（）_ + 。




3. 不应该以特殊字符开始

我曾尝试

  ^（= * [A-ZA-Z]。）（= * [@＃$％^＆AMP（= * \\ D？）;？！*（ ）_ +]）[A-ZA-Z \\ D @＃$％^＆安培;！*（）_ +] {8,20}
 

它的工作原理，但如何从开始的口令限制的特殊字符？此外，如果你有一个更有效的正则表达式比上面提到的请建议的人。

感谢您

解决方案

它的简单，只需要在开始时增加一个字符类

<$p$p><$c$c>^(?=.*[a-zA-Z])(?=.*\\d)(?=.*[!@#$%^&*()_+])[A-Za-z\\d][A-Za-z\\d!@#$%^&*()_+]{7,19}$

• [A-ZA-Z \\ D] 确保第一个字符是字母或数字。




• [A-ZA-Z \\ D @＃$％^＆安培;！*（）_ +] {7,19} 将匹配最低7最大19字符。作为他presceding字符类将消耗单个字符使得字符串作为最低8和最大20个字符的总数，这是必需




• $ 锚在字符串末尾的正则表达式。确保有没有按照我们的的有效的密码的

  VAR模式=新RegExp(/^(?=.*[a-zA-Z])(?=.*\\d)(?=.*[!@#$%^&*()_+])[A-Za-z\\d][A-Za-z\\d!@#$%^&*()_+]{7,19}$/);的console.log（pattern.test（@＃123asdf @＃！））;
= GT;假的console.log（pattern.test（123asdf @＃！））;
= GT;真正的console.log（pattern.test（12AS＃））;
= GT;假
 

I need a regular expression for a password field.

The requirement is:

1. The password Must be 8 to 20 characters in length

2. Must contain at least one letter and one number and a special character from !@#$%^&*()_+.

3. Should not start with a special character

I have tried

^(?=.*[a-zA-Z])(?=.*\d)(?=.*[!@#$%^&*()_+])[A-Za-z\d!@#$%^&*()_+]{8,20}

It works but how do you restrict special characters from beginning the password? Also if you have a more efficient regex than the one mentioned above please suggest.

Thank you

解决方案

Its simple, just add one more character class at the begining

^(?=.*[a-zA-Z])(?=.*\d)(?=.*[!@#$%^&*()_+])[A-Za-z\d][A-Za-z\d!@#$%^&*()_+]{7,19}$

• [A-Za-z\d] Ensures that the first character is an alphabet or digit.

• [A-Za-z\d!@#$%^&*()_+]{7,19} will match minimum 7 maximum 19 character. This is required as he presceding character class would consume a single character making the total number of characters in the string as minimum 8 and maximum 20.

• $ Anchors the regex at the end of the string. Ensures that there is nothing following our valid password

Regex Demo

var pattern = new RegExp(/^(?=.*[a-zA-Z])(?=.*\d)(?=.*[!@#$%^&*()_+])[A-Za-z\d][A-Za-z\d!@#$%^&*()_+]{7,19}$/);

console.log( pattern.test("!@#123asdf!@#") );
=> false

console.log( pattern.test("123asdf!@#") );
=> true

console.log( pattern.test("12as#") );
=> false

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