Allow module to work in both node and browser environments

Author: reteps

js/format.ts

@@ -1,21 +1,34 @@
-import fs from 'node:fs/promises';
-import './wasm_exec.cjs';
-import path from 'node:path';
-import { fileURLToPath } from 'url';
+import './wasm_exec.js';
 
-export interface FormatOptions {
+interface FormatOptions {
     indent: number;
     trailingNewline: boolean;
 }
 
+const isNode: boolean = typeof process !== "undefined" && process.versions != null && process.versions.node != null;
+
 const formatDockerfile = async (fileName: string, options: FormatOptions) => {
+    if (!isNode) {
+        throw new Error('formatDockerfile is only supported in Node.js');
+    }
+    const fs = require('node:fs/promises');
+
     // This would only work in Node.js, so we don't add a wasmDownload function
     const fileBuffer = await fs.readFile(fileName);
     const fileContents = fileBuffer.toString();
     return formatDockerfileContents(fileContents, options);
 }
 
-const getWasmModule = () => fs.readFile(path.resolve(path.dirname(fileURLToPath(import.meta.url)), 'format.wasm'))
+const getWasmModule = () => {
+    if (isNode) {
+        const path = require('node:path');
+        const url = require('node:url');
+        const fs = require('node:fs/promises');
+        return fs.readFile(path.resolve(path.dirname(url.fileURLToPath(import.meta.url)), 'format.wasm'));
+    }
+    // In the browser, we need to fetch the wasm module
+    throw new Error('WASM module not found. Please provide a function to fetch the WASM module.');
+}
 
 const formatDockerfileContents = async (fileContents: string, options: FormatOptions, getWasm: () => Promise<Buffer> = getWasmModule) => {
     const go = new Go()  // Defined in wasm_exec.js
@@ -64,4 +77,4 @@ const formatDockerfileContents = async (fileContents: string, options: FormatOpt
     return result
 }
 
-export { formatDockerfile, formatDockerfileContents }
+export { formatDockerfile, formatDockerfileContents, FormatOptions }

js/format.wasm

@@ -6,7 +6,7 @@
     "test": "echo \"Error: no test specified\" && exit 1",
     "//": "Requires tinygo 0.38.0 or later",
     "build-go": "tinygo build -o format.wasm -target wasm --no-debug",
-    "build-js": "tsc && cp format.wasm wasm_exec.cjs dist",
+    "build-js": "tsc && cp format.wasm wasm_exec.js dist",
     "build": "npm run build-go && npm run build-js"
   },
   "files": [