Check two arrays for a common element

Write a function hasCommonElement(a, b) that checks if two arrays have at least one equal element. In other words, it checks that their intersection is not empty.

• Every element of a and b is a number or a string. The arrays can be empty and can have repeated elements.
• Return a boolean: true if some element of a is also in b, otherwise false.
• Compare with strict equality ===: the number 1 and the string '1' are different, and 'a' and 'A' are different.
• The equal elements can be at any positions in the two arrays.
• If one of the arrays is empty, return false.

A set of the elements of b makes the check fast for long arrays.