Split JavaScript string into array of codepoints? (taking into account “surrogate pairs” but not “grapheme clusters”)

Question

Splitting a JavaScript string into \"characters\" can be done trivially but there are problems if you care about Unicode (and you should care about Unicode).

JavaScr

Answer 1

In ECMAScript 6 you'll be able to use a string as an iterator to get code points, or you could search a string for /./ug, or you could call getCodePointAt(i) repeatedly.

Unfortunately for..of syntax and regexp flags can't be polyfilled and calling a polyfilled getCodePoint() would be super slow (O(n²)), so we can't realistically use this approach for a while yet.

So doing it the manual way:

String.prototype.toCodePoints= function() {
    chars = [];
    for (var i= 0; i=0xD800 && c1<0xDC00 && i+1=0xDC00 && c2<0xE000) {
                chars.push(0x10000 + ((c1-0xD800)<<10) + (c2-0xDC00));
                i++;
                continue;
            }
        }
        chars.push(c1);
    }
    return chars;
}

For the inverse to this see https://stackoverflow.com/a/3759300/18936