JavaScript regex replacement not matching in code but matching in editor

Question

I'm trying to replace occurrences of text in documents with a ugly but normally working regex (tested on regex101 and in the editor, it's matching). But when I run the code, it's not working.

Regex101: https://regex101.com/r/rGmYpP/1

My code:

(async () => {
    const rename = util.promisify(fs.rename);
    const files = await fs.readdir('./working');
    for (let i = 0; i < files.length; i++) {
        const file = files[i];
        const read = async (filePath) => {
            const str = fs.createReadStream(filePath, 'utf8')
                .pipe(new stream.Transform({
                    decodeStrings : false,
                    transform(chunk, encoding, done) {
                        let result = chunk.replace(/\(LAST.*\n.*\n.*\n.*UPDATE/gm, '--------------');
                        done(null, result);
                    }
                }));
            const tempPath = await tempWrite(str);
            await rename(tempPath, filePath+'-output');
        };
        await read('./working/'+file);
    }
})();

Text sample:

OESHNF+Arial*1 [12 0 0 -12 0 0 ]msf
321.639 19.075 mo
(LAST )
[6.672 8.00409 8.00409 7.33191 0 ]xsh
354.938 19.075 mo
(UPDATE )
[8.664 8.00409 8.664 8.00409 7.33191 8.00409 0 ]xsh
406.945 19.075 mo
(OF )

Expected output:

OESHNF+Arial*1 [12 0 0 -12 0 0 ]msf
321.639 19.075 mo
-------------- )
[8.664 8.00409 8.664 8.00409 7.33191 8.00409 0 ]xsh
406.945 19.075 mo
(OF )

Thank you for your help, hope I provided everything.

In the transform-function, add console.log(chunk) to see what you have in the chunk. It might be that you don't have all the text for the regex to match. — some
– some, Commented Jan 21, 2020 at 7:31
I also think you have forgotten a .* after UPDATE: /\(LAST.*\n.*\n.*\n.*UPDATE.*/gm unless you want that unmatched closing bracket. — some
– some, Commented Jan 21, 2020 at 7:34
Have you checked what line-terminators you have in your file? Is it just LF or is it CR+LF? I just tested your code, and it works if it is LF but not for CR+LF. — some
– some, Commented Jan 21, 2020 at 8:05

some · Accepted Answer · 2020-01-21 08:12:11Z

1

I created an example like this:

#!/bin/env node

const fs = require('fs');
const stream = require('stream');

(async () => {
  const file = "test-file.txt";
  const read = async (filePath) => {
      const str = fs.createReadStream(filePath, 'utf8')
          .pipe(new stream.Transform({
              decodeStrings : false,
              transform(chunk, encoding, done) {
                  console.log("chunk", chunk);
                  let result = chunk.replace(/\(LAST.*\n.*\n.*\n.*UPDATE/gm, '--------------');
                  console.log("result", result);
                  done(null, result);
              }
          }));
  };
  await read(file);
})()

And "test-file.txt" like this:

OESHNF+Arial*1 [12 0 0 -12 0 0 ]msf
321.639 19.075 mo
(LAST )
[6.672 8.00409 8.00409 7.33191 0 ]xsh
354.938 19.075 mo
(UPDATE )
[8.664 8.00409 8.664 8.00409 7.33191 8.00409 0 ]xsh
406.945 19.075 mo
(OF )

The regex works if the file uses LF (0x0A) as line terminator, but not if the file uses CR+LF (0x0D + 0x0A) as line terminator.

answered Jan 21, 2020 at 8:12

some

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2 Comments

Kokno Over a year ago

Replacing in the regex \n by \r\n is working, thank you

some Over a year ago

Changing the regexp to /\(LAST.*(\x0D?\x0A).*(\x0D?\x0A).*(\x0D?\x0A).*UPDATE/gm and it will work with both. :)

Toto · Accepted Answer · 2020-01-21 10:19:48Z

1

Use \(LAST[^]+?UPDATE.

Where [^]+? means 1 or more any characters (including newlines), not greedy.

answered Jan 21, 2020 at 10:19

Toto

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