npm chokidar 射击事件两次

Question

I'm using the NPM package chokidar to watch for the new files. I want to execute a function whenever a new file is created or an existing file is updated. The problem is whenever a new file is created the chokidar NPM package fires 2 events that are add and change . Which makes the function execute 2 times.

I tried to add listeners in 2 ways.

Method 1

watcher.on('add', handleFileRequest);
watcher.on('change', handleFileRequest);

Method 2

watcher.on('all', (event, path) => {
        console.log(`event: ${event}`);
        if (event == 'change' || event == 'add') {
            handleFileRequest(path);
        }
    });

Both of the above code snippets call the handleFileRequest method 2 times.

Answer 1

I used a global Array ( processing_requests ) to keep track of the handleFileRequest running for different files. and then before calling handleFileRequest I checked if this function is already running for the same file. If it's already running then I simply skip the execution of handleFileRequest .

watcher.on('all', (event, path) => {
        if ((event == 'change' || event == 'add') && !processing_requests.includes(path)) {
            processing_requests.push(path);
            handleFileRequest(path);
            setTimeout(function() {
                processing_requests = processing_requests.filter(x => x != path);
            }, 500);
        }
    });