fix(js): do not overwrite supported typescript version

packages/js/package.json

@@ -49,6 +49,7 @@
     "ignore": "^5.0.4",
     "js-tokens": "^4.0.0",
     "minimatch": "3.0.5",
+    "semver": "7.3.4",
     "source-map-support": "0.5.19",
     "tslib": "^2.3.0",
     "@nx/devkit": "file:../devkit",

packages/js/src/generators/init/init.spec.ts

@@ -1,6 +1,7 @@
-import { writeJson, readJson, Tree } from '@nx/devkit';
+import { writeJson, readJson, Tree, updateJson } from '@nx/devkit';
 import { createTreeWithEmptyWorkspace } from '@nx/devkit/testing';
 import init from './init';
+import { typescriptVersion } from '../../utils/versions';
 
 describe('js init generator', () => {
   let tree: Tree;
@@ -81,4 +82,38 @@ describe('js init generator', () => {
 
     expect(tree.exists('.vscode/extensions.json')).toBeFalsy();
   });
+
+  it('should install typescript package when it is not already installed', async () => {
+    await init(tree, {});
+
+    const packageJson = readJson(tree, 'package.json');
+    expect(packageJson.devDependencies['typescript']).toBeDefined();
+  });
+
+  it('should overwrite installed typescript version when is not a supported version', async () => {
+    updateJson(tree, 'package.json', (json) => {
+      json.devDependencies = { ...json.devDependencies, typescript: '~4.5.0' };
+      return json;
+    });
+
+    await init(tree, {});
+
+    const packageJson = readJson(tree, 'package.json');
+    expect(packageJson.devDependencies['typescript']).toBe(typescriptVersion);
+  });
+
+  it('should not overwrite installed typescript version when is a supported version', async () => {
+    updateJson(tree, 'package.json', (json) => {
+      json.devDependencies = { ...json.devDependencies, typescript: '~4.7.0' };
+      return json;
+    });
+
+    await init(tree, {});
+
+    const packageJson = readJson(tree, 'package.json');
+    expect(packageJson.devDependencies['typescript']).toBe('~4.7.0');
+    expect(packageJson.devDependencies['typescript']).not.toBe(
+      typescriptVersion
+    );
+  });
 });

packages/js/src/generators/init/init.ts

@@ -6,19 +6,58 @@ import {
   generateFiles,
   GeneratorCallback,
   joinPathFragments,
+  readJson,
   stripIndents,
   Tree,
   updateJson,
   writeJson,
 } from '@nx/devkit';
+import { checkAndCleanWithSemver } from '@nx/devkit/src/utils/semver';
+import { readModulePackageJson } from 'nx/src/utils/package-json';
+import { satisfies, valid } from 'semver';
 import { getRootTsConfigFileName } from '../../utils/typescript/ts-config';
 import {
   nxVersion,
   prettierVersion,
+  supportedTypescriptVersions,
   typescriptVersion,
 } from '../../utils/versions';
 import { InitSchema } from './schema';
 
+async function getInstalledTypescriptVersion(
+  tree: Tree
+): Promise<string | null> {
+  const rootPackageJson = readJson(tree, 'package.json');
+  const tsVersionInRootPackageJson =
+    rootPackageJson.devDependencies?.['typescript'] ??
+    rootPackageJson.dependencies?.['typescript'];
+
+  if (!tsVersionInRootPackageJson) {
+    return null;
+  }
+  if (valid(tsVersionInRootPackageJson)) {
+    // it's a pinned version, return it
+    return tsVersionInRootPackageJson;
+  }
+
+  // it's a version range, check whether the installed version matches it
+  try {
+    const tsPackageJson = readModulePackageJson('typescript').packageJson;
+    const installedTsVersion =
+      tsPackageJson.devDependencies?.['typescript'] ??
+      tsPackageJson.dependencies?.['typescript'];
+    // the installed version matches the package.json version range
+    if (
+      installedTsVersion &&
+      satisfies(installedTsVersion, tsVersionInRootPackageJson)
+    ) {
+      return installedTsVersion;
+    }
+  } finally {
+    return checkAndCleanWithSemver('typescript', tsVersionInRootPackageJson);
+  }
+}
+
 export async function initGenerator(
   tree: Tree,
   schema: InitSchema
@@ -36,7 +75,16 @@ export async function initGenerator(
   };
 
   if (!schema.js) {
-    devDependencies['typescript'] = typescriptVersion;
+    const installedTsVersion = await getInstalledTypescriptVersion(tree);
+
+    if (
+      !installedTsVersion ||
+      !satisfies(installedTsVersion, supportedTypescriptVersions, {
+        includePrerelease: true,
+      })
+    ) {
+      devDependencies['typescript'] = typescriptVersion;
+    }
   }
 
   // https://prettier.io/docs/en/configuration.html

packages/js/src/utils/versions.ts

@@ -8,5 +8,13 @@ export const swcHelpersVersion = '~0.5.0';
 export const swcNodeVersion = '~1.4.2';
 export const tsLibVersion = '^2.3.0';
 export const typesNodeVersion = '18.7.1';
-export const typescriptVersion = '~5.0.2';
 export const verdaccioVersion = '^5.0.4';
+
+// Typescript
+export const typescriptVersion = '~5.0.2';
+/**
+ * The minimum version is currently determined from the lowest version
+ * that's supported by the lowest Angular supported version, e.g.
+ * `npm view @angular/compiler-cli@14.0.0 peerDependencies.typescript`
+ */
+export const supportedTypescriptVersions = '>=4.6.2';