diff --git a/new-package/elm-review-package-tests/check-previews-compile.js b/new-package/elm-review-package-tests/check-previews-compile.js
index 73621f648..067a0ac7d 100644
--- a/new-package/elm-review-package-tests/check-previews-compile.js
+++ b/new-package/elm-review-package-tests/check-previews-compile.js
@@ -14,6 +14,9 @@ for (const example of findPreviewConfigurations()) {
   checkThatExampleCompiles(example);
 }
 
+/**
+ * @param {string} exampleConfiguration
+ */
 function checkThatExampleCompiles(exampleConfiguration) {
   const exampleConfigurationElmJson = require(`${exampleConfiguration}/elm.json`);
 
@@ -62,10 +65,17 @@ and make the necessary changes to make it compile.`
   }
 }
 
+/**
+ * @param {string} config
+ */
 function success(config) {
   console.log(`${Ansi.green('✔')} ${path.relative(root, config)}/ compiles`);
 }
 
+/**
+ * @param {string} exampleConfiguration
+ * @param {Record<string, string>} previewDependencies
+ */
 function checkDepsAreCompatible(exampleConfiguration, previewDependencies) {
   for (const [depName, constraint] of Object.entries(packageDependencies)) {
     if (!(depName in previewDependencies)) {
@@ -94,6 +104,12 @@ function checkDepsAreCompatible(exampleConfiguration, previewDependencies) {
   }
 }
 
+/**
+ * @param {string} exampleConfiguration
+ * @param {string} depName
+ * @param {string} constraint
+ * @param {string} version
+ */
 function checkConstraint(exampleConfiguration, depName, constraint, version) {
   const [minVersion] = constraint.split(' <= v < ').map(splitVersion);
   const previewVersion = splitVersion(version);
@@ -110,6 +126,11 @@ function checkConstraint(exampleConfiguration, depName, constraint, version) {
   }
 }
 
+/**
+ * @param {string} version
+ */
 function splitVersion(version) {
-  return version.split('.').map((n) => Number.parseInt(n, 10));
+  return version
+    .split('.')
+    .map((/** @type {string} */ n) => Number.parseInt(n, 10));
 }
diff --git a/new-package/elm-review-package-tests/helpers/ansi.js b/new-package/elm-review-package-tests/helpers/ansi.js
index fee727b7d..5eaa78f5a 100644
--- a/new-package/elm-review-package-tests/helpers/ansi.js
+++ b/new-package/elm-review-package-tests/helpers/ansi.js
@@ -1,13 +1,22 @@
+/**
+ * @param {string} text
+ */
 function red(text) {
-  return '\u001B[31m' + text + '\u001B[39m';
+  return `\u001B[31m${text}\u001B[39m`;
 }
 
+/**
+ * @param {string} text
+ */
 function green(text) {
-  return '\u001B[32m' + text + '\u001B[39m';
+  return `\u001B[32m${text}\u001B[39m`;
 }
 
+/**
+ * @param {string} text
+ */
 function yellow(text) {
-  return '\u001B[33m' + text + '\u001B[39m';
+  return `\u001B[33m${text}\u001B[39m`;
 }
 
 module.exports = {
diff --git a/new-package/maintenance/update-examples-from-preview.js b/new-package/maintenance/update-examples-from-preview.js
index 9d16a5bec..32b86f49e 100755
--- a/new-package/maintenance/update-examples-from-preview.js
+++ b/new-package/maintenance/update-examples-from-preview.js
@@ -16,6 +16,18 @@ if (require.main === module) {
 
 // Find all elm.json files
 
+/**
+ * @typedef {object} ApplicationElmJson
+ * @property {string[]} source-directories
+ * @property {DependencyList} dependencies
+ */
+
+/**
+ * @typedef {object} DependencyList
+ * @property {Record<string, string>} direct
+ * @property {Record<string, string>} indirect
+ */
+
 function copyPreviewsToExamples() {
   const previewFolders = findPreviewConfigurations();
   for (const folder of previewFolders) {
@@ -23,6 +35,9 @@ function copyPreviewsToExamples() {
   }
 }
 
+/**
+ * @param {string} pathToPreviewFolder
+ */
 function copyPreviewToExample(pathToPreviewFolder) {
   const pathToExampleFolder = `${pathToPreviewFolder}/`.replace(
     /preview/g,
@@ -32,7 +47,10 @@ function copyPreviewToExample(pathToPreviewFolder) {
   fs.copySync(pathToPreviewFolder, pathToExampleFolder, {overwrite: true});
 
   const pathToElmJson = path.resolve(pathToExampleFolder, 'elm.json');
-  const elmJson = fs.readJsonSync(pathToElmJson);
+  const elmJson =
+    /** @type {{ ['source-directories']: string[], dependencies: {direct: Record<string, string>} }} */ (
+      fs.readJsonSync(pathToElmJson)
+    );
 
   // Remove the source directory pointing to the package's src/
   elmJson['source-directories'] = elmJson['source-directories'].filter(
diff --git a/tsconfig.no-implicit-any.json b/tsconfig.no-implicit-any.json
index dd7cd7fb1..af21ac845 100644
--- a/tsconfig.no-implicit-any.json
+++ b/tsconfig.no-implicit-any.json
@@ -58,6 +58,7 @@
     "lib/template-dependencies.js",
     "lib/utils.js",
     "lib/watch.js",
+    "new-package/elm-review-package-tests/*.js",
     "test/jest-helpers/cli.js",
     "test/jest-helpers/types/cli.ts",
     "test/flags.test.js",