To replace the last occurrence of a character in a string in JavaScript, we can use the JavaScript string replace method with a regex.
For instance, we can write:
const str = 'a_b_c';
console.log(str.replace(/_([^_]*)$/, '$1'))
to remove the underscore before the 'c' character.
To do that, we call replace with a regex that searches for the last instance of an underscore with a character after it.
Then in the 2nd argument, we pass in '$1' to remove the underscore from the last instance of the regex match.
