chore: migrate to TypeScript

This change introduces an ESM build which will allow tree shaking. A
CJS build is also provided for backward compatibility.

Author: darrachequesne

.eslintrc.json

@@ -1,4 +1,4 @@
-module.exports = (() => {
+export default (() => {
   if (typeof self !== "undefined") {
     return self;
   } else if (typeof window !== "undefined") {

lib/globalThis.browser.js renamed to lib/globalThis.browser.ts

@@ -0,0 +1 @@
+export default global;

lib/globalThis.js

@@ -0,0 +1,14 @@
+import { Socket } from "./socket.js";
+
+export default (uri, opts) => new Socket(uri, opts);
+
+/**
+ * Expose deps for legacy compatibility
+ * and standalone browser access.
+ */
+export { Socket };
+export { SocketOptions } from "./socket.js";
+export const protocol = Socket.protocol;
+export { Transport } from "./transport.js";
+export { transports } from "./transports/index.js";
+export { installTimerFunctions } from "./util.js";