function reUtf16SurrogatePair() {
	return /[\uD800-\uDBFF][\uDC00-\uDFFF]/;
}
Returns a regular expression to match a UTF-16 surrogate pair.

@returns {RegExp} regular expression

@example
var RE_UTF16_SURROGATE_PAIR = reUtf16SurrogatePair();

var bool = RE_UTF16_SURROGATE_PAIR.test( '\uD800\uDC00' );
// returns true

bool = RE_UTF16_SURROGATE_PAIR.test( 'abc\uD800\uDC00def' );
// returns true

bool = RE_UTF16_SURROGATE_PAIR.test( 'abc' );
// returns false