add script to update npm stats for code resources

package.json

@@ -18,6 +18,7 @@
   "scripts": {
     "start": "ssg dev",
     "build": "ssg export",
-    "update": "node scripts/updateResources.js"
+    "update": "node scripts/updateResources.js",
+    "update-npm-stats": "node scripts/updateNpmStats.js"
   }
 }

scripts/updateNpmStats.js

@@ -0,0 +1,64 @@
+// Fetches and updates the number of monthly npm downloads on each resource.
+// api docs: https://github.com/npm/registry/blob/master/docs/download-counts.md
+
+const fs = require("fs");
+const yaml = require("js-yaml");
+const fetch = require("node-fetch");
+
+const filePath = "data/code.yml";
+const period = "point/last-month";
+const extractNpmPackage = resource => {
+  const matches = resource.name.match(/^`(.+)`$/);
+  return matches && matches[1];
+};
+
+async function updateDownloads() {
+  const data = yaml.safeLoad(fs.readFileSync(filePath, "utf8"));
+
+  const updatedResources = [];
+  for (const resource of data.resources) {
+    const npmPackage = extractNpmPackage(resource);
+    if (!npmPackage) {
+      updatedResources.push(resource);
+      continue;
+    }
+
+    let result = await fetch(
+      `https://api.npmjs.org/downloads/${period}/${npmPackage}`
+    );
+    result = await result.json();
+
+    if (result.error) {
+      if (result.error.includes("not found")) {
+        throw Error(
+          `npm package "${npmPackage}" not found.` +
+            " If the resource is not supposed to be an npm package," +
+            " remove the backticks from its name."
+        );
+      } else {
+        throw Error(`npm error: ${JSON.stringify(result)}`);
+      }
+    }
+
+    updatedResources.push({
+      ...resource,
+      downloads: result.downloads
+    });
+    console.log(`updated ${npmPackage}`);
+  }
+
+  const finishedYaml = {
+    ...data,
+    resources: updatedResources
+  };
+
+  fs.writeFile(filePath, yaml.safeDump(finishedYaml), err => {
+    if (err) {
+      console.log(err);
+    }
+  });
+}
+
+updateDownloads()
+  .then(() => console.log("done!"))
+  .catch(err => console.error(err));