Split / Join.

Third class. Real labels often arrive as one string with a separator.

split(sep) breaks a string into an array. join(sep) is an array method: it glues elements with a separator between them.

Mini example:

const line = "food,rent,fun"; const parts = line.split(","); console.log(parts.join("-"));

Common mistake: looking for join on the string (in JS join lives on arrays); or mixing up the separator for split versus join.