toUTF8Array: Javascript function for encoding a string in UTF8.

toUTF8Array.js

function toUTF8Array(str) {
    var utf8 = [];
    for (var i=0; i < str.length; i++) {
        var charcode = str.charCodeAt(i);
        if (charcode < 0x80) utf8.push(charcode);
        else if (charcode < 0x800) {
            utf8.push(0xc0 | (charcode >> 6), 
                      0x80 | (charcode & 0x3f));
        }
        else if (charcode < 0xd800 || charcode >= 0xe000) {
            utf8.push(0xe0 | (charcode >> 12), 
                      0x80 | ((charcode>>6) & 0x3f), 
                      0x80 | (charcode & 0x3f));
        }
        // surrogate pair
        else {
            i++;
            // UTF-16 encodes 0x10000-0x10FFFF by
            // subtracting 0x10000 and splitting the
            // 20 bits of 0x0-0xFFFFF into two halves
            charcode = 0x10000 + (((charcode & 0x3ff)<<10)
                      | (str.charCodeAt(i) & 0x3ff))
            utf8.push(0xf0 | (charcode >>18), 
                      0x80 | ((charcode>>12) & 0x3f), 
                      0x80 | ((charcode>>6) & 0x3f), 
                      0x80 | (charcode & 0x3f));
        }
    }
    return utf8;
}

toUTF8Array() contains an error which results in incorrect utf-8 encoding for surrogate pairs branch.
In the line containing charcode = ((charcode&0x3ff)<<10)|(str.charCodeAt(i)&0x3ff) its necessary to add 0x010000
to make it work properly.
The error can be easily reproduced using glyph '🜄' which stands for 'Alchemical Symbol For Water'.
This should be rendered to: [240, 159, 156, 132] or hex 0xF0 0x9F 0x9C 0x84 but ends up to be [240, 143, 144, 128].
Correcting the according line to charcode = (((charcode&0x3ff)<<10)|(str.charCodeAt(i)&0x3ff)) + 0x010000; fixes that error.
Btw. function fromUTF8Array() does not suffer from this issue.

The latest version (from Aug 6 2013) no longer has this bug. Did you perchance refer to a previous version of this gist?

The latest version on the top render toUTF8Array('🜄') as (4) [240, 143, 156, 132]
Where as mos0711 pointed out, it should be [240, 159, 156, 132] with his fix.

Hi, I really would like to use this useful snippet in my code but I wondering about a legal stuff like a copyright, licensing etc. I can't see any copyright notice in this snippet nor on @joni github profile. In this case, according to GitHub policy I can't use this code :(
https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/licensing-a-repository

Any thoughts how can I deal with such legal problems? I wondering if maybe @joni you could add some commonly used open source license to your snippet? Or any other ideas?