Check if file exist in Gulp

You can use fs.access

fs.access('/etc/passwd', (err) => {
    if (err) {
        // file/path is not visible to the calling process
        console.log(err.message);
        console.log(err.code);
    }
});

List of available error codes here

Using fs.access() to check for the accessibility of a file before calling fs.open(), fs.readFile() or fs.writeFile() is not recommended. Doing so introduces a race condition, since other processes may change the file’s state between the two calls. Instead, user code should open/read/write the file directly and handle the error raised if the file is not accessible.