webpack: Watcher fails to build sometimes

I’ve been noticing that webpack’s watcher often fails to rebuild when I change a file. I thought there might have been weird issues that had to do with my vagrant situation (where I have another file watcher that copies files over). But now I’m using it on on windows 8.1 (node 0.10.29, webpack 1.5.3).

In my own file watcher that I use for vagrant, I had pretty much the same problem. I was using chokidar, and sometimes files simply weren’t being copied over when they changed. I don’t know the root cause, but I worked around it by setting up a poller that polls file contents for files that I’ve recently changed for up to 50 seconds. If the file changes within that time, it’ll copy it over.

The code I have is:

var seconds = 1000 // from milliseconds

var filesToPoll = {}
function poller() {
    setTimeout(function() {
        Fiber(function() {
            try {
                for(var file in filesToPoll) {
                    var info = filesToPoll[file]
                    if(Date.now() - info.time > 50*seconds && !info.matchFailure) {
                        delete filesToPoll[file] // stop polling it
                    } else if(Date.now() - info.time > 5*seconds && fs.readFileSync(file).toString() !== fs.readFileSync(info.destination).toString()) {
                        info.matchFailure = true
                        console.log(colors.red("File "+file+" doesn't match! Fixing the bitch"))
                        exports.copy(file, info.destination)
                    } else {
                        if(info.matchFailure) {
                            console.log(colors.blue("Match failure corrected for "+file+"!"))
                            info.matchFailure = false
                        }

                    }
                }
            } catch(e) {
                console.log(e.stack.toString().red)
            }
            poller()
        }).run()
    },1000)
}

setTimeout(function() {
    filesToPoll = {} // empty it out after its been given time to set up the watchers
    poller()
},10000)

and to add a file to the poller:

filesToPoll[filePathToCopyOver] = {time: Date.now(), destination: destinationPath}

Originally I just put in the console logs so I could see when files were failing to copy over. After I noticed just how often it was happening, I put in the extra copy logic. I haven’t had a problem with my file watcher since.

So maybe you could use this kind of plug solution if you don’t know why the watcher might not be picking up file changes.