使用特殊条件的正则表达式将字符串替换为哈希（超前/后退）

Question

Lets stay I have the following list of string, in JavaScript (NodeJS) I want to apply a regex one at a time and replace the hash between . and . , but I don't want to replace the word, .style . or .bundle. or . chunk. and it should also work to replace the hash in the case where there is no preceding dots.

// hash starts with number
/css/app.style.7fef363d5a8c4ef2458c.css
/css/app.bundle.7fef363d5a8c4ef2458c.css
/css/app.chunk.7fef363d5a8c4ef2458c.css
/css/app.7fef363d5a8c4ef2458c.css
/css/loading-animation.7fef363d5a8c4ef2458c.css

// hash starts with letter
/css/app.style.b3bcb606396f0c96623a.css
/css/app.bundle.b3bcb606396f0c96623a.css
/css/app.chunk.b3bcb606396f0c96623a.css
/css/app.b3bcb606396f0c96623a.css

// no preceeding dot separated name before the hash
/css/loading-animation.b3bcb606396f0c96623a.css
/css/app.b3bcb606396f0c96623a.js

// It should not affect items without a hash
/fonts/MaterialIcons-Regular.eot
/fonts/MaterialIcons-Regular.svg

The result should be

// hash starts with number
/css/app.style.css
/css/app.bundle.css
/css/app.chunk.css
/css/app.css
/css/loading-animation.css

// hash starts with letter
/css/app.style.css
/css/app.bundle.css
/css/app.chunk.css
/css/app.css

// no preceeding dot separated name before the hash
/css/loading-animation.css
/css/app.js

// It should not affect items without a hash
/fonts/MaterialIcons-Regular.eot
/fonts/MaterialIcons-Regular.svg

I tried hard and the closest I got was this

 const manifest = {};
 stats.assets.map(asset => asset.name)
    .sort()
    .forEach((file) => {
       let regEx = /\.(?!(?:[A-Za-z]))(([^.]*))\./gi
       let passTest = regEx.test(file);
       let key = file.replace(regEx, '.');
       console.log(file, passTest, key);
       manifest[key] = file;
    });

But that only replaces the hash starting with the number, and ignores all the rest.

I also tried /\\.(?!(?:[A-Za-z]))(([^.]*))\\./gi; but that just replaced the first occurrence of .something.

I also had no luck with negative lookbehinds (it is a new feature in JS according to here and here )

What is the proper regex for this?

Answer 1

How about this?

[^.]+\.(?=[^.]+$)

It looks for any non-period characters followed by a period ( [^.]+\\. ) followed by (using a lookahead) a series of non-period characters ( [^.]+ ) and an end-of-line ( $ ).

https://regex101.com/r/5QfED2/1