What is the output of the expression [...'Lydia'];?

The expression [..., 'Lydia'] uses the spread operator (...) in conjunction with a string. The spread operator in JavaScript takes an iterable, such as a string or an array, and expands it into individual elements.

When applied to a string, the spread operator separates each character of the string into individual elements. Therefore, when you spread the string 'Lydia', it converts each character ('L', 'y', 'd', 'i', and 'a') into its own element in an array.

As a result, the output of the expression is an array containing each character of the string as separate elements: ["L", "y", "d", "i", "a"]. This demonstrates a clear understanding of how the spread operator works with iterables, yielding the correct response.