add wasm example

examples/wasm.js

@@ -0,0 +1,8 @@
+const base64 = "AGFzbQEAAAABBgFgAX8BfwMCAQAHBwEDRmliAAAKHgEcACAAQQJJBH8gAAUgAEEBaxAAIABBAmsQAGoLCwANBG5hbWUBBgEAA0ZpYg==";
+const buffer = Uint8Array.from(atob(base64), c => c.charCodeAt(0));
+const wasmModule = new WebAssembly.Module(buffer);
+const instance = new WebAssembly.Instance(wasmModule, {});
+const fib = instance.exports.Fib;
+for (let i = 0; i < 10; i++) {
+  console.log(`fib(${i}) = ${fib(i)}`);
+}