feat(code): Wrote asm.js example

closes #12

Author: bahmutov

README.md

@@ -46,6 +46,7 @@ implementations are available
 * [dependency injection](src/14-dependency-injection.js)
 * [immutable data](src/15-immutable.js)
 * [async await](src/16-async-await.js)
+* [asm.js](src/17-asm.js)
 
 [post]: http://glebbahmutov.com/blog/journey-from-procedural-to-reactive-javascript-with-stops/
 

package.json

@@ -54,7 +54,8 @@
         "node src/13-transducers.js",
         "node src/14-dependency-injection.js",
         "node src/15-immutable.js",
-        "node src/16-async-await.js"
+        "node src/16-async-await.js",
+        "node src/17-asm.js"
       ],
       "pre-push": [],
       "post-commit": [],

src/17-asm.js

@@ -0,0 +1,42 @@
+'use asm';
+
+// main point is to provide primitive type information
+// (unsigned bytes in this case) to the engine
+// by using typed arrays and '|0' operators on the individual variables
+
+// Any suggestions for improving this Asm.js example are welcome
+// https://github.com/bahmutov/javascript-journey/issues
+
+// numbers is an array of unsigned bytes
+var numbers = new Uint8Array([3, 1, 7]);
+// constant is an integer
+var constant = 2|0;
+
+// multiplication of two integers
+function mul(a, b) {
+  a = a|0;
+  b = b|0;
+  return a * b;
+}
+function print(n) {
+  n = n|0;
+  console.log(n);
+}
+var byConstant = mul.bind(null, constant);
+
+function iterate(list, cb) {
+  var n = list.length|0;
+  var k = 0;
+  for (; k < n; k += 1) {
+    cb(list[k]|0);
+  }
+}
+
+// while v8 in node does not offer performance improvements,
+// other environments, like Firefox can
+var start = process.hrtime();
+iterate(numbers, byConstant);
+var elapsed = process.hrtime(start);
+console.log('multiplication took %d seconds %d nanoseconds',
+  elapsed[0], elapsed[1]);
+