JavaScript Introduction (Microsoft)

Microsoft's JavaScript Introduction lives on edX at edx.org, and you can audit it for free, which gives you the video lessons and reading materials. The graded work and the verified certificate sit behind a payment. Microsoft hosts it on edX, so this is the place to take it. We are not in edX's affiliate program, so we earn nothing whether you audit or buy the certificate. This is a true beginner course, covering variables, functions, arrays, objects, and the DOM, so it's a fine first step if you have never written JavaScript. Audit it free to learn the basics, or pay if you want the certificate. For a more hands-on path afterward, Scrimba's free JavaScript course pairs well with it.

The course is beginner level, and edX lists it at about 3 weeks of study at 2 to 4 hours a week (source: edx.org/learn/javascript/microsoft-introduction-to-javascript).