buffer: implement btoa and atob

Signed-off-by: James M Snell <[email protected]> PR-URL: #37529Fixes: #3462 Reviewed-By: Anna Henningsen <[email protected]> Reviewed-By: Matteo Collina <[email protected]>

Author: jasnell

doc/api/buffer.md

@@ -3277,6 +3277,44 @@ While, the `Buffer` object is available as a global, there are additional
 `Buffer`-related APIs that are available only via the `buffer` module
 accessed using `require('buffer')`.
 
+### `buffer.atob(data)`
+<!-- YAML
+added: REPLACEME
+-->
+
+*`data`{any} The Base64-encoded input string.
+
+Decodes a string of Base64-encoded data into bytes, and encodes those bytes
+into a string using Latin-1 (ISO-8859-1).
+
+The `data` may be any JavaScript-value that can be coerced into a string.
+
+**This function is only provided for compatibility with legacy web platform APIs
+and should never be used in new code, because they use strings to represent
+binary data and predate the introduction of typed arrays in JavaScript.
+For code running using Node.js APIs, converting between base64-encoded strings
+and binary data should be performed using `Buffer.from(str, 'base64')` and
+`buf.toString('base64')`.**
+
+### `buffer.btoa(data)`
+<!-- YAML
+added: REPLACEME
+-->
+
+*`data`{any} An ASCII (Latin1) string.
+
+Decodes a string into bytes using Latin-1 (ISO-8859), and encodes those bytes
+into a string using Base64.
+
+The `data` may be any JavaScript-value that can be coerced into a string.
+
+**This function is only provided for compatibility with legacy web platform APIs
+and should never be used in new code, because they use strings to represent
+binary data and predate the introduction of typed arrays in JavaScript.
+For code running using Node.js APIs, converting between base64-encoded strings
+and binary data should be performed using `Buffer.from(str, 'base64')` and
+`buf.toString('base64')`.**
+
 ### `buffer.INSPECT_MAX_BYTES`
 <!-- YAML
 added: v0.5.4

lib/buffer.js

@@ -1211,14 +1211,50 @@ if (internalBinding('config').hasIntl){
 };
 }
 
+letDOMException;
+
+constlazyInvalidCharError=hideStackFrames((message,name)=>{
+if(DOMException===undefined)
+DOMException=internalBinding('messaging').DOMException;
+thrownewDOMException('Invalid character','InvalidCharacterError');
+});
+
+functionbtoa(input){
+// TODO(@jasnell): The implementation here has not been performance
+// optimized in any way.
+input=`${input}`;
+for(letn=0;n<input.length;n++){
+if(input[n].charCodeAt(0)>0xff)
+lazyInvalidCharError();
+}
+constbuf=Buffer.from(input,'latin1');
+returnbuf.toString('base64');
+}
+
+constkBase64Digits=
+'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
+
+functionatob(input){
+// TODO(@jasnell): The implementation here has not been performance
+// optimized in any way.
+input=`${input}`;
+for(letn=0;n<input.length;n++){
+if(!kBase64Digits.includes(input[n]))
+lazyInvalidCharError();
+}
+returnBuffer.from(input,'base64').toString('latin1');
+}
+
 module.exports={
  Blob,
  Buffer,
  SlowBuffer,
  transcode,
 // Legacy
  kMaxLength,
- kStringMaxLength
+ kStringMaxLength,
+ btoa,
+ atob,
 };
 
 ObjectDefineProperties(module.exports,{