Learn the standards and principles first and the abstractions second, when you understand the limitations and pain points that make abstractions worth the overhead.
Templating, pre-/post-processors, transpilers, frameworks and libraries are all there to make it easier to produce HTML, CSS and JavaScript.
Don't under-rate HTML either. You need good HTML to make an accessible UI. You need good HTML to write good CSS, JavaScript, tests...... bad HTML is a bad foundation, things built on a bad foundation are shaky.