Get UTF-8 Codepoint from UTF-8 Hex-Num array in JavaScript

[JS]GetUTF8CodePoint

function getCodePoint(array) {

	/*-----------------------------------------------------------------------------------------
	[UCS-2 (UCS-4)]      [bit pattern]        [1st byte]  [2nd byte]  [3rd byte]  [4th byte]
	U+ 0000..  U+007F    00000000-0xxxxxxx     0xxxxxxx
	U+ 0080..  U+07FF    00000xxx-xxyyyyyy     110xxxxx    10yyyyyy
	U+ 0800..  U+FFFF    xxxxyyyy-yyzzzzzz     1110xxxx    10yyyyyy    10zzzzzz    
	U+10000..U+1FFFFF    00000000-000wwwxx     11110www    10xxxxxx    10yyyyyy    10zzzzzz
	                     -xxxxyyyy-yyzzzzzzz
	------------------------------------------------------------------------------------------*/

	var bytes = array.length;
	var firstShift = (bytes === 1) ? 0 : (bytes + 1);
	var codePoint =	ar[0] & (0xFF >> firstShift);
	for(var n = 1; n < bytes; n++) {
		codePoint <<= 6;
		codePoint += array[n] & 0x3F;	// Mask 0x00111111
	}
	return codePoint;
}