This small script continuously builds a LaTeX file in the background and outputs all files into a folder of your choice (default output/). Of note is the build file (default output/build.pdf) which is what you should open in a pdf viewer of your choice while editing your LaTeX document.
It is less jarring and looks cleaner than other build systems (e.g. latexmk -pvc) (The final build file only updates on a successful and complete build. Other build tools will write an incomplete pdf that your pdf viewer can't handle, leading to a broken pdf for a few seconds while you are editing) It may also be faster than latexmk, but this is untested.
See the original stack overflow post for motivation, usage instruction, and some useful vim configuration.
Sioyek works well as a pdf reader since (unlike zathura, okular, and evince) when it reloads a pdf, it doesn't re-render the entire screen, leading to a much less jarring experience.