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Strange behavior with `fs.watch` on file with JSON stringified -> first update isn't emitted if too fast after `fs.watch`

Open Apokalypt opened this issue 9 months ago • 6 comments

Node.js Version

v18.17.1

NPM Version

9.6.7

Operating System

23.2.0 Darwin

Subsystem

fs

Description

I would like to watch changes on a file storing JSON stringified data but the watcher created with fs.watch is not emitted if the change happen to quickly after the call of fs.watch. The strange thing is that if the content is only a text (without JSON format) the watcher emit the event correctly...

Minimal Reproduction

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

const filePath = path.join(__dirname, 'test.json');
// Create the file if it doesn't exist
if (!fs.existsSync(filePath)) {
    fs.writeFileSync(filePath, "{ }");
}

fs.watch(filePath, (eventType, filename) => {
    console.log(`Event type is: ${eventType}`);
    if (filename) {
        console.log(`Filename provided: ${filename}`);
    } else {
        console.log('Filename not provided');
    }
});

fs.writeFileSync(filePath, "{ \"test\": \"test\", \"test2\": \"test2\" }"); // same with JSON.stringify(...)
// Listener above is called if we replace line above with:
// fs.writeFileSync(filePath, "very ok or not but I need a longer text to test something...");

Output

Expected

Event type is: change
Filename provided: test.json

Received

Nothing

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Apokalypt avatar May 21 '24 14:05 Apokalypt