Determines whether the specified code point is a digit character.
true for characters with general category "Nd" (decimal digit numbers). Beginning with Unicode 4, this is the same as testing for the Numeric_Type of Decimal.
Parameters
codepoint
The int codepoint value (e.g. 0x2603 for U+2603 SNOWMAN), or the character encoded as a UTF-8 string (e.g. "\u{2603}")
Return Values
Returns true if
codepoint is a digit character, false if not. Returns null on failure.