求用于验证Cloudinary Public ID的JavaScript正则表达式

Let's nail this regex for validating Cloudinary Public IDs! First, let's recap the exact rules we need to enforce:

• All printable characters are allowed except the reserved characters: ? & # \ % < > .
• Cannot start or end with a space ( ) or slash (/)

Why Your Original Regex Failed #

Your initial attempt ^[^\s\\]+[^?&#\%<>]+$ had a few key issues:

• You used HTML entities like & instead of raw characters (&) — regex doesn't parse HTML entities
• It didn't exclude the reserved character .
• It didn't account for the "no slash at start/end" rule
• The structure required at least two characters, which misses valid single-character Public IDs

The Correct Regex #

Here's a regex that covers all the requirements, with clear logic:

const cloudinaryPublicIdRegex = /^(?![\s/])(?!.*[\s/]$)(?!.*[\?&#\\%<>.]).+$/;

Breakdown of the Regex #

Let's break down each part to understand how it works:

• ^(?![\s/]): Ensures the string doesn't start with a space or slash
• (?!.*[\s/]$): Makes sure the string doesn't end with a space or slash
• (?!.*[\?&#\\%<>.]: Checks that no reserved characters appear anywhere in the string
• .+: Requires at least one character (since empty Public IDs aren't valid)

Test Cases #

Let's verify with some examples:

• ✅ Valid: my-profile_photo、blog/posts summer-vacation、custom-id!@$
• ❌ Invalid: my-id (starts with space)、photos/ (ends with slash)、image?.png (contains ?)、file.name (contains .)

Alternative Concise Version #

If you prefer a more compact regex without lookaheads (though slightly less readable), you can use this:

const cloudinaryPublicIdRegex = /^[^\s/?&#\\%<>](?:[^\?&#\\%<>]*[^\s/?&#\\%<>])?$/;

This works by:

• Matching a valid start character (not space, slash, or reserved)
• Allowing any number of non-reserved characters in the middle
• Ending with a valid character (same rules as the start)
• The ? makes the middle+end part optional, supporting single-character IDs

内容的提问来源于stack exchange，提问作者steve-o