Convert loader to ESM

.eslintrc.js

@@ -87,13 +87,18 @@ module.exports = {
         "es6": true
       },
       files: [
-        "**/*.js"
+        "**/*.js",
+        "**/*.mjs",
+        "**/*.cjs"
       ],
       rules: {
         // Node's support for ESM is still not great, but this rule is likely
-        // to become activated once compatibility doesn't suck anymore.
+        // to become activated once ESM-by-default becomes generally usable.
         "@typescript-eslint/no-var-requires": "off",
 
+        // There are no types in JavaScript
+        "@typescript-eslint/explicit-module-boundary-types": "off",
+
         // Enforcing to remove function parameters on stubs makes code less
         // maintainable, so we instead allow unused function parameters.
         "no-unused-vars": [

lib/loader/index.d.ts

@@ -5,7 +5,6 @@ export interface ResultObject {
   instance: WebAssembly.Instance;
 }
 
-
 /** WebAssembly imports with an optional env object and two levels of nesting. */
 export type Imports = {
   [key: string]: Record<string,unknown>;

lib/loader/index.js

@@ -1,32 +1,19 @@
-"use strict";
-
 // Runtime header offsets
 const ID_OFFSET = -8;
 const SIZE_OFFSET = -4;
 
 // Runtime ids
 const ARRAYBUFFER_ID = 0;
 const STRING_ID = 1;
-// const ARRAYBUFFERVIEW_ID = 2;
 
 // Runtime type information
 const ARRAYBUFFERVIEW = 1 << 0;
 const ARRAY = 1 << 1;
 const STATICARRAY = 1 << 2;
-// const SET = 1 << 3;
-// const MAP = 1 << 4;
 const VAL_ALIGN_OFFSET = 6;
-// const VAL_ALIGN = 1 << VAL_ALIGN_OFFSET;
 const VAL_SIGNED = 1 << 11;
 const VAL_FLOAT = 1 << 12;
-// const VAL_NULLABLE = 1 << 13;
 const VAL_MANAGED = 1 << 14;
-// const KEY_ALIGN_OFFSET = 15;
-// const KEY_ALIGN = 1 << KEY_ALIGN_OFFSET;
-// const KEY_SIGNED = 1 << 20;
-// const KEY_FLOAT = 1 << 21;
-// const KEY_NULLABLE = 1 << 22;
-// const KEY_MANAGED = 1 << 23;
 
 // Array(BufferView) layout
 const ARRAYBUFFERVIEW_BUFFER_OFFSET = 0;
@@ -299,7 +286,7 @@ function isModule(src) {
 }
 
 /** Asynchronously instantiates an AssemblyScript module from anything that can be instantiated. */
-async function instantiate(source, imports = {}) {
+export async function instantiate(source, imports = {}) {
   if (isResponse(source = await source)) return instantiateStreaming(source, imports);
   const module = isModule(source) ? source : await WebAssembly.compile(source);
   const extended = preInstantiate(imports);
@@ -308,21 +295,17 @@ async function instantiate(source, imports = {}) {
   return { module, instance, exports };
 }
 
-exports.instantiate = instantiate;
-
 /** Synchronously instantiates an AssemblyScript module from a WebAssembly.Module or binary buffer. */
-function instantiateSync(source, imports = {}) {
+export function instantiateSync(source, imports = {}) {
   const module = isModule(source) ? source : new WebAssembly.Module(source);
   const extended = preInstantiate(imports);
   const instance = new WebAssembly.Instance(module, imports);
   const exports = postInstantiate(extended, instance);
   return { module, instance, exports };
 }
 
-exports.instantiateSync = instantiateSync;
-
 /** Asynchronously instantiates an AssemblyScript module from a response, i.e. as obtained by `fetch`. */
-async function instantiateStreaming(source, imports = {}) {
+export async function instantiateStreaming(source, imports = {}) {
   if (!WebAssembly.instantiateStreaming) {
     return instantiate(
       isResponse(source = await source)
@@ -337,10 +320,8 @@ async function instantiateStreaming(source, imports = {}) {
   return { ...result, exports };
 }
 
-exports.instantiateStreaming = instantiateStreaming;
-
 /** Demangles an AssemblyScript module's exports to a friendly object structure. */
-function demangle(exports, extendedExports = {}) {
+export function demangle(exports, extendedExports = {}) {
   extendedExports = Object.create(extendedExports);
   const setArgumentsLength = exports["__argumentsLength"]
     ? length => { exports["__argumentsLength"].value = length; }
@@ -424,4 +405,9 @@ function demangle(exports, extendedExports = {}) {
   return extendedExports;
 }
 
-exports.demangle = demangle;
+export default {
+  instantiate,
+  instantiateSync,
+  instantiateStreaming,
+  demangle
+};

lib/loader/package.json

@@ -21,18 +21,30 @@
   "bugs": {
     "url": "https://github.com/AssemblyScript/assemblyscript/issues"
   },
-  "main": "index.js",
-  "types": "index.d.ts",
+  "type": "module",
+  "main": "./umd/index.js",
+  "exports": {
+    ".": {
+      "require": "./umd/index.js",
+      "import": "./index.js"
+    }
+  },
+  "types": "./index.d.ts",
+  "module": "./index.js",
   "scripts": {
     "asbuild": "npm run asbuild:default && npm run asbuild:legacy",
     "asbuild:default": "node ../../bin/asc tests/assembly/index.ts -b tests/build/default.wasm",
     "asbuild:legacy": "node ../../bin/asc tests/assembly/index.ts --disable mutable-globals -b tests/build/legacy.wasm",
-    "test": "node tests"
+    "test": "node tests",
+    "build": "npx esm2umd loader index.js > umd/index.js",
+    "prepublishOnly": "npm run build"
   },
   "files": [
-    "index.d.ts",
     "index.js",
+    "index.d.ts",
     "package.json",
-    "README.md"
+    "README.md",
+    "umd/index.js",
+    "umd/package.json"
   ]
 }

lib/loader/tests/index.js

@@ -1,8 +1,12 @@
-var fs = require("fs");
-var assert = require("assert");
-var inspect = require("util").inspect;
+import fs from "fs";
+import assert from "assert";
+import { inspect } from "util";
+import { dirname } from 'path';
+import { fileURLToPath } from 'url';
 
-var loader = require("..");
+import loader from "../index.js";
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
 
 test("default.wasm");
 test("legacy.wasm");
@@ -11,9 +15,8 @@ testInstantiate("default.wasm");
 testInstantiate("legacy.wasm");
 
 function test(file) {
-  var buffer = fs.readFileSync(__dirname + "/build/" + file);
-  var result = loader.instantiateSync(buffer, {});
-  const exports = result.exports;
+  const buffer = fs.readFileSync(__dirname + "/build/" + file);
+  const exports = loader.instantiateSync(buffer, {}).exports;
 
   console.log(inspect(exports, true, 100, true));