Javascript's comma operator.

The behavior of the comma operator in JavaScript can seem odd at first, but it actually has a pretty simple purpose: it allows you to evaluate multiple expressions, but only the result of the last expression is returned. JavaScript evaluates expressions from left to right, and with the comma operator, it executes each expression in sequence but discards the results of all except the final one. This is useful in cases where you want to perform side effects in a single line (like variable assignments or function calls) but only care about the final value for the next step.