(JavaScript) base64 字符串 和 ArrayBuffer 之间转换

base64 --> ArrayBuffer

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

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

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

ArrayBuffer --> base64

function arrayBufferToBase64(buffer) {
         var binary = '';
         var bytes = new Uint8Array(buffer);
         var len = bytes.byteLength;
         for (var i = 0; i < len; i++) {
               binary += String.fromCharCode(bytes[i]);
         }
         return window.btoa(binary);
}