正则表达式需要在字符串的开头匹配特殊字符 [英] Regex needed for matching special characters at start of string

问题描述

我需要修改现有的正则表达式，以便在字符串值的开头支持特殊字符。

I require a modification to my existing regex to support special characters at the starting of a string value .

我目前有这个表达式：

/^(?=.*[a-zA-Z])(?=.*\d)(?=.*[!@#$%^&*()_+])[A-Za-z\d][A-Za-z\d!@#$%^&*()_+.]{7,63}$/

这接受8-64个字符之间的任何字符串，其中包含至少1个数字，字母表以及以下特殊符号：！@＃$％^& *（）_ +。

This accepts any string between 8-64 chars , which has atleast 1 number , alphabet and a special symbol from the following : !@#$%^&*()_+.

如何识别特殊字符输入值？

How do I get it to recognize special characters at the start of an input value ?

要匹配的字符串：

.abc@1234
*abc@1234
abc@1234.
a@b.c1234

谢谢

推荐答案

您需要删除 [A-Za-z \ n] 并替换 {7 ，63} ， {8,64} 。

使用

^(?=.*[a-zA-Z])(?=.*\d)(?=.*[!@#$%^&*()_+])[A-Za-z\d!@#$%^&*()_+.]{8,64}$

请参阅演示

也许，您还想将。添加回前瞻，以便它是还需要：

Perhaps, you also want to add the . back to the lookahead, so that it was also required:

^(?=.*[a-zA-Z])(?=.*\d)(?=.*[!@#$%^&*()_+.])[A-Za-z\d!@#$%^&*()_+.]{8,64}$
                                         ^

为确保特殊符号不会立即发生，请添加a （？！。* [！@＃$％^& *（）_ +。] {2}） 负向前瞻：

To make sure the special symbols do not occur in immediate succession, add a (?!.*[!@#$%^&*()_+.]{2}) negative lookahead:

^(?=.*[a-zA-Z])(?=.*\d)(?=.*[!@#$%^&*()_+.])(?!.*[!@#$%^&*()_+.]{2})[A-Za-z\d!@#$%^&*()_+.]{8,64}$
                                            ^^^^^^^^^^^^^^^^^^^^^^^^

请参阅此演示

请注意，很多人会对使用如此长的正则表达式的可维护性问题大肆宣传。您可以将条件拆分为单独的代码段，也可以使用带注释的多行正则表达式：

Note that a lot of people here would scream about mainainability issue of using such a long regex. You can either split the conditions into separate pieces of code, or use a multiline regex with comments:

var rx = RegExp("^" + // Start of string
               "(?=.*[a-zA-Z])" + // Require a letter
               "(?=.*\\d)" + // Require a digit
               "(?=.*[!@#$%^&*()_+])" + // Require a special symbol
               "(?!.*[!@#$%^&*()_+.]{2})" + // Disallow consecutive special symbols
               "[A-Za-z\\d!@#$%^&*()_+.]{8,64}" + // 8 to 64 symbols from the set
               "$");

var re = RegExp("^" + // Start of string
               "(?=.*[a-zA-Z])" + // Require a letter
               "(?=.*\\d)" + // Require a digit
               "(?=.*[!@#$%^&*()_+])" + // Require a special symbol
               "(?!.*[!@#$%^&*()_+.]{2})" + // Disallow consecutive special symbols
               "[A-Za-z\\d!@#$%^&*()_+.]{8,64}" + // 8 to 64 symbols from the set
               "$", "gm");

var str = '.abc@1234\n*abc@1234\nabc@1234.\na@b.c1234\n*abc@1234\nabc@1234.\na@b.c1234\na@b.#c123\na@__c1234';
while ((m = re.exec(str)) !== null) {
  document.body.innerHTML += m[0] + "<br/>";
}

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