JS正则表达式求助：限制点号首尾位置及重复等规则实现

Hey there! Let's fix this regex step by step. First, let's recap your exact requirements to make sure we cover everything:

• Allowed characters: uppercase/lowercase letters, numbers, ! # $ % & ' * + - / = ? ^ _ { | } ~`, and dots (`.`)
• Dots can't be at the start or end of the string
• Dots can't appear consecutively

Why Your Current Regex Isn't Working #

Your attempt /^[^.]([\^><@,.]+)/ has a few key issues:

• It includes characters like ^, >, <, @, , that aren't in your allowed list
• It doesn't enforce the "no consecutive dots" rule or prevent dots from appearing at the end of the string
• It only matches the start of the string, not the entire input (missing the $ anchor to lock the end)

The Correct Regex #

Here's a regex that meets all your requirements perfectly:

^[A-Za-z0-9!#$%&'*+\-/=?^_`{|}~](?:\.?[A-Za-z0-9!#$%&'*+\-/=?^_`{|}~])*$

Breakdown of the Regex #

Let's break this down piece by piece so you understand exactly how it enforces your rules:

• ^: Anchors the match to the start of the string (ensures we don't match partial inputs)
• [A-Za-z0-9!#$%&'*+\-/=?^_{|}~]`: Matches the first character, which must be a non-dot allowed character (solves the "no dot at start" rule)
• (?:...): A non-capturing group (we don't need to save this part separately) that repeats zero or more times:
  • \.?: An optional dot (if present)
  • [A-Za-z0-9!#$%&'*+\-/=?^_{|}~]`: Immediately follows any dot, ensuring the dot is never followed by another dot (solves the "no consecutive dots" rule)
• $: Anchors the match to the end of the string, ensuring the last character is always a non-dot allowed character (solves the "no dot at end" rule)

Test Cases to Verify #

• ✅ Valid: Test123!$, a.b.c, user.name_123~
• ❌ Invalid: .startWithDot, endWithDot., double..dots, invalid@char

内容的提问来源于stack exchange，提问作者Vivek