I want to develop a browser game available on mobile devices. I'm wondering what is the best programming language for browser game development?

This question did not belong in the Writing forum. Moved to For Beginners, where “what's the best language” and “what's the best engine” questions are usually asked.

@anh2 Javascript is the language you'll be using for client side web apps, including games.

https://developer.mozilla.org/en-US/docs/Games/Tutorials/2D_Breakout_game_pure_JavaScript/Create_the_Canvas_and_draw_on_it​

Please don't use javascript for graphical games, it is slow and inefficient. Use something that compiles to WASM if you actually care about your players and their battery life.

If you just do a pen-and-paper style game with buttons, number tables, and a few images, your game would be server-side, though, and then you'd probably use something like php or maybe Go for the server.