Sounds good, send a PR

@sokra i think we should implement this in webpack@5 before stable release, can we move this in yes?

The PR was merged last year, but I think more docs would be great, as it seems like the change is only mentioned vaguely once in https://webpack.js.org/blog/2020-10-10-webpack-5-release/#new-watching, no other documentation.

It also captures more information about filesystem while watching. It now captures mtimes and watches event times, as well as information about missing files. For this, the WatchFileSystem API changed a little bit. While on it we also converted Arrays to Sets and Objects to Maps.

Luckily I was able to figure it out - the tests were esp. helpful - and changed our usage of the plugin mentioned by @maxwoo-houzz

as there are already a couple people (including me) that use it.

like so:

class WatchRunPlugin {
    apply(compiler) {
        compiler.hooks.watchRun.tap('WatchRun', (comp) => {
            if (comp.modifiedFiles) {
                const changedFiles = Array.from(comp.modifiedFiles, (file) => `\n  ${file}`).join('');
                console.log('===============================');
                console.log('FILES CHANGED:', changedFiles);
                console.log('===============================');
            }
        });
    }
}

Yes, let's documented this

We have 4 variables here:

// Timestamps for files
this.compiler.fileTimestamps;
// Timestamps for directories
this.compiler.contextTimestamps;
// Removed files
this.compiler.removedFiles;
// Modified files
this.compiler.modifiedFiles;

// Timestamps for directories
this.compiler.contextTimestamps;

for directories, I am seeing empty objects in compiler.contextTimestamps - is that expected?

// Removed files
this.compiler.removedFiles;
// Modified files
this.compiler.modifiedFiles;

is there also anything like addedFiles?

is there also anything like addedFiles?

I done a console.log of each keys in compiler that contains the string file or File, and it output this :

compiler.outputFileSystem
compiler.intermediateFileSystem
compiler.inputFileSystem
compiler.watchFileSystem
compiler.modifiedFiles
compiler.removedFiles
compiler._assetEmittingWrittenFiles
compiler._assetEmittingPreviousFiles