Deep learn Node.js or use Express()

Hi guys, I am currently learning Node.js and Express(). The course that I’m taking exploits Express a lot and I find it very convenient. However, like Vanilla Javascript, I’m thinking about deep learning Node.js first, and then continue with Express().

Is this a good approach for me?

Basically, Express() help reducing a lot of lines of codes, and I can understand how it works in Node.js too.