Gulp Basics: How to update from Gulp 3 to Gulp 4

So I went through the "Gulp Basics" course and I ran into a bunch of errors when trying to compile the final project. It took some adjustments of the package.json file so I wanted to outline the steps.

1. Change all tasks that have 3 parameters

If you're getting this error:

AssertionError [ERR_ASSERTION]: Task function must be specified

the following will fix the issue. Find any task that looks like this:

gulp.task("taskName", ["otherTasks"], function () {
    /* other code */
}))

and change it to this:

gulp.task("taskName", gulp.series(["otherTasks"], function () {
    /* other code */
}))

Don't forget to add a closing parenthesis since there's a new one after gulp.series(

2. Install the gulp-cli globally

If you're now getting this error:

TypeError: Cannot read property 'apply' of undefined

the following will fix the issue. In the cli (e.g. terminal or CMD), type this:

npm i -g gulp-cli

3. Update the syntax for the watchFiles task

Assuming you've tried compiling your code after each step, the next (and final) error you'll run into is caused by the syntax in the watchFiles task.

Update this:

gulp.watch("scss/**/*.scss", ["compileSass"])
gulp.watch("js/main.js", ["concatScripts"])

to this:

gulp.watch("scss/**/*.scss", gulp.parallel(["compileSass"]))
gulp.watch("js/main.js", gulp.parallel(["concatScripts"]))

At this point, if the code is not compiling, throw out your computer and buy a new one.