Run results for: ArrayBuffer

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/73.0.3683.86 Chrome/73.0.3683.86 Safari/537.36 Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.80 Safari/537.36

Browser: Chromium 73

Operating system: Windows

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
Cached decode	11279.9 Ops/sec
Simple decode	110491.7 Ops/sec

Script Preparation code:

var str = "aa34a5b6c5acb67acb5acb678acb6ac4b5a6c7b5a4c3b45a67c8b76a54cb34a5c6b7aa34a5b6c5acb67acb5acb678acb6ac4b5a6c7b5a4c3b45a67c8b76a54cb34a5c6b7aa34a5b6c5acb67acb5acb678acb6ac4b5a6c7b5a4c3b45a67c8b76a54cb34a5c6b7aa34a5b6c5acb67acb5acb678acb6ac4b5a6c7b5a4c3b45a67c8b76a54cb34a5c6b7aa34a5b6c5acb67acb5acb678acb6ac4b5a6c7b5a4c3b45a67c8b76a54cb34a5c6b7aa34a5b6c5acb67acb5acb678acb6ac4b5a6c7b5a4c3b45a67c8b76a54cb34a5c6b7aa34a5b6c5acb67acb5acb678acb6ac4b5a6c7b5a4c3b45a67c8b76a54cb34a5c6b7aa34a5b6c5acb67acb5acb678acb6ac4b5a6c7b5a4c3b45a67c8b76a54cb34a5c6b7aa34a5b6c5acb67acb5acb678acb6ac4b5a6c7b5a4c3b45a67c8b76a54cb34a5c6b7aa34a5b6c5acb67acb5acb678acb6ac4b5a6c7b5a4c3b45a67c8b76a54cb34a5c6b7aa34a5b6c5acb67acb5acb678acb6ac4b5a6c7b5a4c3b45a67c8b76a54cb34a5c6b7aa34a5b6c5acb67acb5acb678acb6ac4b5a6c7b5a4c3b45a67c8b76a54cb34a5c6b7";

var chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

// Use a lookup table to find the index.
var lookup = new Uint8Array(256);
for (var i = 0; i < chars.length; i++) {
  lookup[i] = chars.charCodeAt(i);
}

function _base64ToArrayBufferFaster(base64) {
    var binary_string =  window.atob(base64);
    var len = binary_string.length;
    var bytes = new Uint8Array( len );
    for (var i = 0; i < len; i++)        {
        bytes[i] = lookup[binary_string[i]];
    }
    return bytes.buffer;
}

function _base64ToArrayBuffer(base64) {
    var binary_string =  window.atob(base64);
    var len = binary_string.length;
    var bytes = new Uint8Array( len );
    for (var i = 0; i < len; i++)        {
        bytes[i] = binary_string.charCodeAt(i);
    }
    return bytes.buffer;
}

Tests:

Cached decode
_base64ToArrayBufferFaster(str);
Simple decode
_base64ToArrayBuffer(str);

Run results for: ArrayBuffer

Cached decode

Simple decode