Strange gulp syntax

Question

I am using Gulp v3.9.1, and have run across a gulpfile that is using a syntax that is foreign to me. None of the tasks with this syntax will run.

gulp.task ('serve', [ 'js.lint', 'test' ], () => {
        onError = eatError;

        browserSync.init ({
            ui: false,
            files: [
                'index2.html',
                'tpl/**/*',
                opts.srcDir + '/assets/img/**/*',
                opts.srcDir + '/assets/less/**/*',
                opts.srcDir + '/app/**/*',
                opts.testDir + '/**/*',
                'src/main/coverage/**/*'
            ],
            proxy: {
                target: "localhost:8080",
                proxyOptions: {
                    xfwd: true
                }
            }
        });

        gulp.watch ([ 'gulpfile.js', opts.srcDir + '/app/**/*', opts.testDir + '/**/*' ], [ 'js.lint', 'test' ]);
    });

In particular, I am referring to the () => on the first line. That is what gulp is complaining about. That syntax looks a little similar to a CoffeScript gulpfile I found, but I am not sure what it is. The project using this gulpfile has a ton of packages, which I am sifting through right now to see if they have anything to do with this syntax. I want to know what the () => represents, and how to get tasks using this syntax to run.

Answer 1

That's the ES2015 syntax for an anonymous function with the outer scope's this as the context.

To get that syntax to work with gulp, make sure the file name is gulpfile.babel.js and not just gulpfile.js. Recent versions of gulp know to look for that file name and transpile it on-the-fly before running it, provided you have Babel installed.