Add support for serving esm files directly from unpkg (#152)

The following changes have been made:
* utils getEntry()
  allow a ${v} placeholder which supports passing the version to
  unpkg and converts a "master" branch name to the "latest" version
* render
  support an "esm" type that serves the files directly
* render_code
  bypass typescript file annotation for raw files (implied by "esm")

src/app_test.js

@@ -11,6 +11,7 @@ exports.tests = async function tests() {
   assert.deepEqual(proxy("/x/install/foo/bar.js"), {
     entry: {
       name: "install",
+      type: "github",
       raw: { type: "github", owner: "denoland", repo: "deno_install" },
       url: "https://raw.githubusercontent.com/denoland/deno_install/master/",
       repo: "https://github.com/denoland/deno_install"
@@ -20,13 +21,35 @@ exports.tests = async function tests() {
   assert.deepEqual(proxy("/x/install@v0.1.2/foo/bar.js"), {
     entry: {
       name: "install",
+      type: "github",
       raw: { type: "github", owner: "denoland", repo: "deno_install" },
       url: "https://raw.githubusercontent.com/denoland/deno_install/v0.1.2/",
       repo: "https://github.com/denoland/deno_install"
     },
     path: "foo/bar.js"
   });
 
+  database.__test_version = {
+    type: "esm",
+    url: "https://unpkg.com/__test_version@${v}/",
+    repo: "https://github.com/__test_versionorg/repo"
+  };
+  assert.deepEqual(proxy("/x/__test_version@master/file.js"), {
+    entry: {
+      name: "__test_version",
+      type: "esm",
+      raw: {
+        type: "esm",
+        url: "https://unpkg.com/__test_version@${v}/",
+        repo: "https://github.com/__test_versionorg/repo"
+      },
+      url: "https://unpkg.com/__test_version@latest/",
+      repo: "https://github.com/__test_versionorg/repo"
+    },
+    path: "file.js"
+  });
+  delete database.__test_version;
+
   let event = require("./testdata/req1.json");
   const context = require("./testdata/context1.json");
   let counter = 0;

src/render.js

@@ -43,6 +43,14 @@ module.exports = async function render(
     } else {
       return response.success(transpiled, "application/javascript");
     }
+  } else if (entry.type === "esm") {
+    if (showHTMLVersion) {
+      return require("./render_code")(pathname, content, entry, {
+        raw: true
+      });
+    } else {
+      return response.success(content, "application/javascript");
+    }
   } else if (showHTMLVersion) {
     // Accept header present, this is a web browser, so display something
     // pretty.

src/render_code.js

@@ -8,8 +8,8 @@ const { transformModuleSpecifier } = require("./transpile_code");
 const { annotate } = require("./analyze_code");
 const renderBreadcrumbs = require("./breadcrumbs");
 
-function getLines(pathname, code) {
-  if (pathname.endsWith(".ts") || pathname.endsWith(".js")) {
+function getLines(pathname, code, opts) {
+  if (!opts.raw && (pathname.endsWith(".ts") || pathname.endsWith(".js"))) {
     try {
       return {
         err: null,
@@ -31,7 +31,8 @@ function getLines(pathname, code) {
 module.exports = function renderCode(pathname, code, entry, opts = {}) {
   const url = `https://deno.land${pathname}`;
 
-  const { err, lines: escapedLines } = getLines(pathname, code);
+  const { err, lines: escapedLines } = getLines(pathname, code, opts);
+
   const lineNumberedCode = escapedLines
     .map((content, i) => {
       const line = i + 1;

src/utils.js

@@ -28,18 +28,32 @@ exports.walkAST = function walkAST(node, cb) {
  */
 exports.getEntry = function getEntry(name, branch = "master") {
   const rawEntry = DATABASE[name];
-  if (rawEntry.type === "url") {
+  if (!rawEntry) {
+    return null;
+  } else if (rawEntry.type === "url") {
     return {
       name,
       raw: rawEntry,
+      type: "url",
       url: rawEntry.url.replace(/\$\{b}/, branch),
       repo: rawEntry.repo.replace(/\$\{b}/, branch)
     };
   }
+  if (rawEntry.type === "esm") {
+    const version = branch === "master" ? "latest" : branch;
+    return {
+      name,
+      raw: rawEntry,
+      type: "esm",
+      url: rawEntry.url.replace(/\$\{v}/, version),
+      repo: rawEntry.repo.replace(/\$\{v}/, version)
+    };
+  }
   if (rawEntry.type === "github") {
     return {
       name,
       raw: rawEntry,
+      type: "github",
       url: `https://raw.githubusercontent.com/${rawEntry.owner}/${
         rawEntry.repo
       }/${branch}${rawEntry.path || "/"}`,