The following enquiry functions are built in:

• isFinite()

• isNaN()

This operator can behave as if it were a function:

• typeof

These enquiry functions are available in other languages and we have documented them elsewhere with example scripts to simulate their functionality:

• isalnum()

• isalpha()

• iscntrl()

• isdigit()

• isgraph()

• islower()

• isodigit()

• isprint()

• ispunct()

• isspace()

• isupper()

• isxdigit()