deno run --allow-net --allow-read --allow-write script.ts [YEAR OF ADVENT OF CODE] [YOUR SESSION COOKIE HERE]
In 2021, to warm-up and start learning Typescript and Deno, I made a script to download the input and the first challenge for each day. Run the command above with the year and your session cookie from adventofcode.com, this will create a subfolder on the current directory for each available day. Besides the input.txt, an initial solution.ts file will be saved with the text from that day's challenge as a comment and some boilerplate code that I've found to be useful as all puzzles involve handling some line-by-line input.