uint8 Array和Base64互轉

轉自 stackoverflow

最近在做截圖上傳時需要數據轉換，網上找的解決方案記錄一下。

unction uint8arrayToBase64(u8Arr) {
    let CHUNK_SIZE = 0x8000; //arbitrary number
    let index = 0;
    let length = u8Arr.length;
    let result = '';
    let slice;
    while (index < length) {
        slice = u8Arr.subarray(index, Math.min(index + CHUNK_SIZE, length));
        result += String.fromCharCode.apply(null, slice);
        index += CHUNK_SIZE;
    }
    // web image base64圖片格式: "data:image/png;base64," + b64encoded;
    // return  "data:image/png;base64," + btoa(result);
    return btoa(result);
}

function base64ToUint8Array(base64String) {
    let padding = '='.repeat((4 - base64String.length % 4) % 4);
    let base64 = (base64String + padding)
        .replace(/\-/g, '+')
        .replace(/_/g, '/');

    let rawData = window.atob(base64);
    let outputArray = new Uint8Array(rawData.length);

    for (var i = 0; i < rawData.length; ++i) {
        outputArray[i] = rawData.charCodeAt(i);
    }
    return outputArray;
}