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));
}

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