build: cronjob cannot install angular snapshot builds

Apparently the script that also ran on `TravisCI` does not work on MacOS, nor on CircleCI because it's not
guaranteed that the default `awk` supports storing `match()` results in an array that can print individual
match groups.

Author: devversion

.circleci/config.yml

@@ -279,7 +279,7 @@ jobs:
     - *restore_cache
     - *yarn_install
 
-    - run: ./scripts/install-angular-snapshots.sh
+    - run: node ./scripts/install-angular-snapshots.js
     - run: ./scripts/circleci/run-local-browser-tests.sh
 
 # ----------------------------------------------------------------------------------------

scripts/install-angular-snapshots.js

@@ -0,0 +1,42 @@
+/*
+ * Script that re-installs all Angular dependencies using the GitHub build snapshots. We need to
+ * do this after the locked node modules have been installed because otherwise `--frozen-lockfile`
+ * would complain about outdated lock files.
+ */
+
+const path = require('path');
+const fs = require('fs');
+const execSync = require('child_process').execSync;
+const packageJsonPath = path.join(__dirname, '../package.json');
+const packageJson = require(packageJsonPath);
+
+/** 
+ * Updates all Angular dependencies for a given type by replacing the version with a Github URL
+ * that refers to the corresponding Github builds repository.
+ * @param dependencyType Either `dependencies` or `devDependencies` 
+*/
+function updateAngularDependencies(dependencyType) {
+  Object.keys(packageJson[dependencyType])
+    .filter(depName => depName.startsWith('@angular/'))
+    .forEach(depName => {
+      packageJson[dependencyType][depName] = `github:angular/${depName.split('/')[1]}-builds`
+    });
+}
+
+// Update `dependencies` and `devDependencies` in the "packageJson" object, so that
+// we can write the changes to disk afterwards. We cannot just run `yarn add ${all_deps}` because
+// Yarn will complain that some dependencies are already set up in the package.json file.
+updateAngularDependencies('dependencies');
+updateAngularDependencies('devDependencies');
+
+// Write the dependencies changes to the original "package.json" file.
+fs.writeFileSync(packageJsonPath, JSON.stringify(packageJson, null, 2));
+
+// Run "yarn install" in order to install the packages that have been written to the package.json.
+execSync('yarn install', {
+  stdio: 'inherit',
+  shell: true,
+  cwd: path.join(__dirname, '../')
+});
+
+console.log('Finished installing the Angular snapshot builds.');