diff --git a/js/unit_tests.ts b/js/unit_tests.ts
index 5c32f710fd..103e89d894 100644
--- a/js/unit_tests.ts
+++ b/js/unit_tests.ts
@@ -17,3 +17,5 @@ import "./symlink_test.ts";
 import "./platform_test.ts";
 import "./text_encoding_test.ts";
 import "./trace_test.ts";
+
+import "../website/app_test.js";
diff --git a/website/app.js b/website/app.js
index 66151b6cac..612cc7af08 100644
--- a/website/app.js
+++ b/website/app.js
@@ -1,18 +1,46 @@
+// Copyright 2018 the Deno authors. All rights reserved. MIT license.
+
+export async function getJson(path) {
+  return (await fetch(path)).json();
+}
+
 const benchmarkNames = ["hello", "relative_import"];
-
-(async () => {
-  const data = await (await fetch("./data.json")).json();
-
-  const execTimeColumns = benchmarkNames.map(name => [
+export function createExecTimeColumns(data) {
+  return benchmarkNames.map(name => [
     name,
     ...data.map(d => {
       const benchmark = d.benchmark[name];
-      return benchmark ? benchmark.mean : 0;
+      const meanValue = benchmark ? benchmark.mean : 0;
+      return meanValue || 0;
     })
   ]);
+}
 
-  const binarySizeList = data.map(d => d.binary_size || 0);
-  const sha1List = data.map(d => d.sha1);
+export function createBinarySizeColumns(data) {
+  return [["binary_size", ...data.map(d => d.binary_size || 0)]];
+}
+
+export function createSha1List(data) {
+  return data.map(d => d.sha1);
+}
+
+// Formats the byte sizes e.g. 19000 -> 18.55 KB
+// Copied from https://stackoverflow.com/a/18650828
+export function formatBytes(a, b) {
+  if (0 == a) return "0 Bytes";
+  var c = 1024,
+    d = b || 2,
+    e = ["Bytes", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"],
+    f = Math.floor(Math.log(a) / Math.log(c));
+  return parseFloat((a / Math.pow(c, f)).toFixed(d)) + " " + e[f];
+}
+
+export async function main() {
+  const data = await getJson("./data.json");
+
+  const execTimeColumns = createExecTimeColumns(data);
+  const binarySizeColumns = createBinarySizeColumns(data);
+  const sha1List = createSha1List(data);
 
   c3.generate({
     bindto: "#exec-time-chart",
@@ -27,7 +55,7 @@ const benchmarkNames = ["hello", "relative_import"];
 
   c3.generate({
     bindto: "#binary-size-chart",
-    data: { columns: [["binary_size", ...binarySizeList]] },
+    data: { columns: binarySizeColumns },
     axis: {
       x: {
         type: "category",
@@ -40,15 +68,4 @@ const benchmarkNames = ["hello", "relative_import"];
       }
     }
   });
-})();
-
-// Formats the byte sizes e.g. 19000 -> 18.55KB
-// Copied from https://stackoverflow.com/a/18650828
-function formatBytes(a, b) {
-  if (0 == a) return "0 Bytes";
-  var c = 1024,
-    d = b || 2,
-    e = ["Bytes", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"],
-    f = Math.floor(Math.log(a) / Math.log(c));
-  return parseFloat((a / Math.pow(c, f)).toFixed(d)) + " " + e[f];
 }
diff --git a/website/app_test.js b/website/app_test.js
new file mode 100644
index 0000000000..74ccb406d7
--- /dev/null
+++ b/website/app_test.js
@@ -0,0 +1,89 @@
+// Copyright 2018 the Deno authors. All rights reserved. MIT license.
+
+import { test, testPerm, assertEqual } from "../js/test_util.ts";
+import {
+  createBinarySizeColumns,
+  createExecTimeColumns,
+  createSha1List,
+  formatBytes
+} from "./app.js";
+
+const regularData = [
+  {
+    created_at: "2018-01-01T01:00:00Z",
+    sha1: "abcdef",
+    binary_size: 100000000,
+    benchmark: {
+      hello: {
+        mean: 0.05
+      },
+      relative_import: {
+        mean: 0.06
+      }
+    }
+  },
+  {
+    created_at: "2018-01-02T01:00:00Z",
+    sha1: "012345",
+    binary_size: 110000000,
+    benchmark: {
+      hello: {
+        mean: 0.055
+      },
+      relative_import: {
+        mean: 0.065
+      }
+    }
+  }
+];
+
+const irregularData = [
+  {
+    created_at: "2018-01-01T01:00:00Z",
+    sha1: "123",
+    benchmark: {
+      hello: {},
+      relative_import: {}
+    }
+  },
+  {
+    created_at: "2018-02-01T01:00:00Z",
+    sha1: "456",
+    benchmark: {}
+  }
+];
+
+test(function createExecTimeColumnsRegularData() {
+  const columns = createExecTimeColumns(regularData);
+  assertEqual(columns, [
+    ["hello", 0.05, 0.055],
+    ["relative_import", 0.06, 0.065]
+  ]);
+});
+
+test(function createExecTimeColumnsIrregularData() {
+  const columns = createExecTimeColumns(irregularData);
+  assertEqual(columns, [["hello", 0, 0], ["relative_import", 0, 0]]);
+});
+
+test(function createBinarySizeColumnsRegularData() {
+  const columns = createBinarySizeColumns(regularData);
+  assertEqual(columns, [["binary_size", 100000000, 110000000]]);
+});
+
+test(function createBinarySizeColumnsIrregularData() {
+  const columns = createBinarySizeColumns(irregularData);
+  assertEqual(columns, [["binary_size", 0, 0]]);
+});
+
+test(function createSha1ListRegularData() {
+  const sha1List = createSha1List(regularData);
+  assertEqual(sha1List, ["abcdef", "012345"]);
+});
+
+test(function formatBytesPatterns() {
+  assertEqual(formatBytes(18000), "17.58 KB");
+  assertEqual(formatBytes(1800000), "1.72 MB");
+  assertEqual(formatBytes(180000000), "171.66 MB");
+  assertEqual(formatBytes(18000000000), "16.76 GB");
+});
diff --git a/website/index.html b/website/index.html
index 7cb8b02989..6ee68af2fb 100644
--- a/website/index.html
+++ b/website/index.html
@@ -11,7 +11,10 @@
   <div id="binary-size-chart"></div>
   <script src="https://unpkg.com/d3@5.7.0/dist/d3.min.js"></script>
   <script src="https://unpkg.com/c3@0.6.7/c3.min.js"></script>
-  <script src="./app.js"></script>
+  <script type="module">
+  import { main } from "./app.js";
+  main();
+  </script>
 </body>
 </html>