Javascript Convert String to Byte Array

StringToByteArray.js

var url = "Hello World";
var data = [];
for (var i = 0; i < url.length; i++){  
    data.push(url.charCodeAt(i));
}

This is not byte array, this is char code list.

function unpack(str) {
    var bytes = [];
    for(var i = 0; i < str.length; i++) {
        var char = str.charCodeAt(i);
        bytes.push(char >>> 8);
        bytes.push(char & 0xFF);
    }
    return bytes;
}

@techird Your code is char code list or byte array?

I think this might also work

[...Buffer.from('hello world')]

@techird its only latin
use this to, code not my

function toUTF8Array(str) {
    let utf8 = [];
    for (let i = 0; i < str.length; i++) {
        let 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;
}

@dinigo yes, works, equal to java str.getBytes(Charsets.UTF_8)

@Insidexa Good job ！

@Insidexa Imo, these codes are used to convert the char codes from UTF-16 to UTF-8, because the default internal encoding of JS strings is UTF-16. However if all I need is a UTF-16 byte array, I don't have to do so many complex checks and bit operations.

also Array.from("111122222333344444555")

if you want to convert to array of numbers you could use

Array.from("1111222223333444445556", (x) => Number(x))

if you want to convert to array of numbers you could use

Array.from("1111222223333444445556", (x) => Number(x))

Array.from("\x00", (x) => Number(x))

results in [NaN]!

If you handle raw bytes in a 0..255 space: Better use a slightly different version with charCodeAt. I didnt test how it behaves with unicode chars.

Array.from("1111222223333444445556", , (x) => x.charCodeAt(0))

function unpack(str) {
    var bytes = [];
    for(var i = 0; i < str.length; i++) {
        var char = str.charCodeAt(i);
        bytes.push(char >>> 8);
        bytes.push(char & 0xFF);
    }
    return bytes;
}

this is the correct way to extract the bytes a JavaScript string is made of

String.charCodeAt() returns a 16 bit unsigned integer, it must be split into two bytes if exceeds 0xff