assert(toUTFindex(`hello world`, 7) == 7); assert(toUTFindex(`hello world`w, 7) == 7); assert(toUTFindex(`hello world`d, 7) == 7); assert(toUTFindex(`Ma Chérie`, 6) == 7); assert(toUTFindex(`Ma Chérie`w, 7) == 7); assert(toUTFindex(`Ma Chérie`d, 7) == 7); assert(toUTFindex(`さいごの果実 / ミツバチと科学者`, 3) == 9); assert(toUTFindex(`さいごの果実 / ミツバチと科学者`w, 9) == 9); assert(toUTFindex(`さいごの果実 / ミツバチと科学者`d, 9) == 9);
Given a UCS index n into str, returns the UTF index. So, n is how many code points into the string the code point is, and the array index of the code unit is returned.