Browser support

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## [Unreleased][unreleased]
 
+- Add browser polyfill
 - Using optional chaining operator
 
 ## [1.2.1][] - 2022-07-07

dist/.eslintrc.json

@@ -1,4 +1,5 @@
 {
+  "extends": "../.eslintrc.json",
   "parserOptions": {
     "sourceType": "module"
   }

dist/metavm.d.ts

@@ -0,0 +1,25 @@
+export type Context = {
+  [k: string]: unknown & ({ bind?: never } | { call?: never });
+};
+
+export type ScriptOptions = {
+  timeout: number;
+  isWorker: boolean;
+  context: Context;
+};
+
+export function createContext(context?: Context): Context;
+
+export class MetaScript {
+  constructor(name: string, src: string, options?: ScriptOptions);
+  name: string;
+  script: string;
+  context: Context;
+  exports: any;
+}
+
+export function createScript(
+  name: string,
+  src: string,
+  options?: ScriptOptions,
+): MetaScript;

dist/metavm.mjs

@@ -0,0 +1,90 @@
+const script = `onmessage = (e) => {
+  const func =
+    new Function(\`return \${e.data.source}\`)()(...e.data.values);
+  const value = typeof func === 'function' ? func() : func;
+  postMessage({
+    value: value,
+    name: e.data.name,
+  });
+};`;
+
+const RUN_OPTIONS = {
+  timeout: 1000,
+  inWorker: true,
+};
+
+class VMWorker {
+  constructor() {
+    this.calls = new Map();
+    this.worker = new Worker(URL.createObjectURL(new Blob([script])));
+    this.worker.addEventListener('message', (event) => {
+      const { name, value } = event.data;
+      if (!this.calls.has(name)) return;
+      if (value) this.calls.get(name).resolve(value);
+      else this.calls.get(name).reject(`Couldn't execute script ${name}`);
+    });
+  }
+
+  execScript(name, script, context, { inWorker, timeout }) {
+    const source = `(${Object.keys(context)}) => ${script}`;
+    const values = Object.values(context);
+    if (!inWorker) {
+      const func = Function(`return ${source}`)()(...values);
+      return typeof func === 'function' ? func() : func;
+    }
+    return new Promise((resolve, reject) => {
+      this.worker.postMessage({
+        name,
+        source,
+        values,
+      });
+      this.calls.set(name, { resolve, reject });
+      setTimeout(() => {
+        reject('Response timeout');
+      }, timeout);
+    });
+  }
+}
+
+const worker = new VMWorker();
+
+// adding it to keep compability with packages that already using it
+// most of the browser apis are already available when running script
+// can be used for additional libriries
+const COMMON_CONTEXT = Object.freeze({});
+
+const EMPTY_CONTEXT = Object.freeze({});
+
+const createContext = (context) => {
+  if (context === undefined) return EMPTY_CONTEXT;
+  return context;
+};
+
+class MetaScript {
+  constructor(name, src, options = {}) {
+    this.name = name;
+    this.src = src;
+    this.runOptions = { ...RUN_OPTIONS, ...options };
+
+    this.context = options.context ? options.context : createContext();
+  }
+
+  get exports() {
+    return worker.execScript(
+      this.name,
+      this.src,
+      this.context,
+      this.runOptions,
+    );
+  }
+}
+
+const createScript = (name, src, options) => new MetaScript(name, src, options);
+
+export {
+  createContext,
+  createScript,
+  MetaScript,
+  EMPTY_CONTEXT,
+  COMMON_CONTEXT,
+};