byte-array-to-string.js

function decode(text) {
    if (!text)
        return "";

    //string to byte[]
    let byteArr = [];
    for (let i = 0; i < text.length; i++) {
        byteArr.push(text.charCodeAt(i));
    }

    let str = "";
    for (let i = 0; i < byteArr.length;) {
        let binary = byteArr[i].toString(2);
        let head = binary.match(/^1+?(?=0)/);

        if (head && binary.length == 8) {
            //該字元需要幾個位元組
            let bytesLength = head[0].length;
            //第一個位元組的實際資料區                 
            let body = binary.slice(bytesLength);
            for (let j = 1; j < bytesLength; j++) {
                //組合資料
                body += byteArr[i + j].toString(2).slice(2);
            }
            str += String.fromCharCode(parseInt(body, 2));
            i += bytesLength;
        } else {
            str += String.fromCharCode(byteArr[i]);
            i++;
        }
    }
    return str;
}