chore: remove Buffer usage for browser environments (#423)

Closes #418

Author: curran

src/base64-string.ts

@@ -0,0 +1,20 @@
+// Base64 string encoding and decoding module.
+// Uses Buffer for Node.js and btoa/atob for browser environments.
+// We use TextEncoder/TextDecoder for browser environments because
+// they can handle non-ASCII characters, unlike btoa/atob.
+
+export const stringToBase64 =
+    typeof Buffer !== 'undefined'
+        ? (str: string) => Buffer.from(str).toString('base64')
+        : (str: string) =>
+              btoa(
+                  new TextEncoder()
+                      .encode(str)
+                      .reduce((acc, byte) => acc + String.fromCharCode(byte), ''),
+              );
+
+export const base64ToString =
+    typeof Buffer !== 'undefined'
+        ? (str: string) => Buffer.from(str, 'base64').toString()
+        : (str: string) =>
+              new TextDecoder().decode(Uint8Array.from(atob(str), (c) => c.charCodeAt(0)));

src/embed.ts

@@ -21,6 +21,7 @@ import {
 } from './print/node-helpers';
 import { CommentNode, ElementNode, Node, ScriptNode, StyleNode } from './print/nodes';
 import { extractAttributes } from './lib/extractAttributes';
+import { base64ToString } from './base64-string';
 
 const {
     builders: { group, hardline, softline, indent, dedent, literalline },
@@ -253,7 +254,7 @@ function getSnippedContent(node: Node) {
     const encodedContent = getAttributeTextValue(snippedTagContentAttribute, node);
 
     if (encodedContent) {
-        return Buffer.from(encodedContent, 'base64').toString('utf-8');
+        return base64ToString(encodedContent);
     } else {
         return '';
     }

src/lib/snipTagContent.ts

@@ -1,3 +1,5 @@
+import { base64ToString, stringToBase64 } from '../base64-string';
+
 export const snippedTagContentAttribute = '✂prettier:content✂';
 
 const scriptRegex =
@@ -42,7 +44,7 @@ export function snipScriptAndStyleTagContent(source: string): string {
             if (match.startsWith('<!--') || withinOtherSpan(index)) {
                 return match;
             }
-            const encodedContent = Buffer.from(content).toString('base64');
+            const encodedContent = stringToBase64(content);
             const newContent = `<${tagName}${attributes} ${snippedTagContentAttribute}="${encodedContent}">${placeholder}</${tagName}>`;
 
             // Adjust the spans because the source now has a different content length
@@ -97,7 +99,7 @@ const regex = /(<\w+.*?)\s*✂prettier:content✂="(.*?)">.*?(?=<\/)/gi;
 
 export function unsnipContent(text: string): string {
     return text.replace(regex, (_, start, encodedContent) => {
-        const content = Buffer.from(encodedContent, 'base64').toString('utf8');
+        const content = base64ToString(encodedContent);
         return `${start}>${content}`;
     });
 }