address comments

playground/index-raw.html

@@ -115,7 +115,7 @@ <h3>Options</h3>
 </code></pre>
 
 <h3>Streaming</h3>
-<p>There is no support for streaming. However, it can be implemented in userland.</p>
+<p>There is no support for streaming. However, <a href="https://github.com/tc39/proposal-arraybuffer-base64/blob/main/stream.mjs">it can be implemented in userland</a>.</p>
 
 <footer>
   <p>Thanks for reading! If you got this far, you should try out the proposal in your browser's developer tools on this page, and submit feedback on <a href="https://github.com/tc39/proposal-arraybuffer-base64">GitHub</a>.</p>

spec.html

@@ -81,16 +81,20 @@ <h1>Uint8Array.fromBase64 ( _string_ [ , _options_ ] )</h1>
     1. Let _lastChunkSize_ be _inputLength_ modulo 4.
     1. If _lastChunkSize_ is 1, then
       1. Throw a *SyntaxError* exception.
-    1. Else if _lastChunkSize_ is 2 or _lastChunkSize_ is 3, then
-      1. Append U+0041 (LATIN CAPITAL LETTER A) to _lastChunkSize_ a total of (4 - _lastChunkSize_) times.
-    1. Let _bytes_ be the unique sequence of bytes such that applying the base64 encoding specified in section 4 of RFC 4648 to that sequence would produce _input_.
-    1. Let _byteLength_ be the length _bytes_.
+    1. Else if _lastChunkSize_ is 2, then
+      1. Append U+0041 (LATIN CAPITAL LETTER A) to _input_ twice.
+    1. Else if _lastChunkSize_ is 3, then
+      1. Append U+0041 (LATIN CAPITAL LETTER A) to _input_.
+    1. Let _bytes_ be the unique (possibly empty) sequence of bytes such that applying the base64 encoding specified in section 4 of RFC 4648 to that sequence would produce _input_.
+    1. Let _byteLength_ be the length of _bytes_.
     1. If _lastChunkSize_ is 2, then
       1. If _strict_ is *true* and _bytes_[_byteLength_ - 2] is not 0, throw a *SyntaxError* exception.
       1. Remove the final 2 elements of _bytes_.
+      1. Set _byteLength_ to _byteLength_ - 2.
     1. Else if _lastChunkSize_ is 3, then
       1. If _strict_ is *true* and _bytes_[_byteLength_ - 1] is not 0, throw a *SyntaxError* exception.
       1. Remove the final element of _bytes_.
+      1. Set _byteLength_ to _byteLength_ - 1.
     1. Let _result_ be ? AllocateTypedArray(*"Uint8Array"*, %Uint8Array%, %Uint8Array.prototype%, _byteLength_).
     1. Set the value at each index of _result_.[[ViewedArrayBuffer]].[[ArrayBufferData]] to the value at the corresponding index of _bytes_.
     1. Return _result_.

test-polyfill.mjs

@@ -49,7 +49,7 @@ let illegal = [
   'Z＋==', // U+FF0B 'Fullwidth Plus Sign'
   'Zg\u00A0==', // nbsp
   'Zg\u2009==', // thin space
-  'Zg\u2028==', // thin space
+  'Zg\u2028==', // line separator
 ];
 test('illegal characters', async t => {
   for (let string of malformedPadding) {