let budget = 1000000000;

// It's hard for the human eye to detect what is the actual order in here.

// But, by using the Numerical Separators, it can be rewritten in the following way:

let budget = 1_000_000_000;

Via https://dev.to/shubhambattoo/numeric-separators-p4b

Check the caniuse:
https://caniuse.com/mdn-javascript_grammar_numeric_separators