feat: auto detect and preserve format

.prettierignore

@@ -0,0 +1 @@
+test/fixture/tsconfig.json

package.json

@@ -26,7 +26,7 @@
     "test:types": "tsc --noEmit --module esnext --skipLibCheck --moduleResolution node ./test/*.test.ts"
   },
   "dependencies": {
-    "confbox": "^0.1.6",
+    "confbox": "^0.1.7",
     "mlly": "^1.6.1",
     "pathe": "^1.1.2"
   },

src/index.ts

@@ -3,7 +3,7 @@ import { dirname, resolve, isAbsolute } from "pathe";
 import { ResolveOptions as _ResolveOptions, resolvePath } from "mlly";
 import { findFile, FindFileOptions, findNearestFile } from "./utils";
 import type { PackageJson, TSConfig } from "./types";
-import { parseJSONC } from "confbox";
+import { parseJSONC, parseJSON, stringifyJSON, stringifyJSONC } from "confbox";
 
 export * from "./types";
 export * from "./utils";
@@ -63,7 +63,7 @@ export async function readPackageJSON(
     return cache.get(resolvedPath)!;
   }
   const blob = await fsp.readFile(resolvedPath, "utf8");
-  const parsed = JSON.parse(blob) as PackageJson;
+  const parsed = parseJSON(blob) as PackageJson;
   cache.set(resolvedPath, parsed);
   return parsed;
 }
@@ -77,7 +77,7 @@ export async function writePackageJSON(
   path: string,
   package_: PackageJson,
 ): Promise<void> {
-  await fsp.writeFile(path, JSON.stringify(package_, undefined, 2));
+  await fsp.writeFile(path, stringifyJSON(package_));
 }
 
 /**
@@ -113,7 +113,7 @@ export async function writeTSConfig(
   path: string,
   tsconfig: TSConfig,
 ): Promise<void> {
-  await fsp.writeFile(path, JSON.stringify(tsconfig, undefined, 2));
+  await fsp.writeFile(path, stringifyJSONC(tsconfig));
 }
 
 /**

test/fixture/tsconfig.json

@@ -1,14 +1,17 @@
 {
-  // Comment
-  "compilerOptions": {
+  "compilerOptions": { // Comment
     "target": "ESNext",
     "module": "ESNext",
     "moduleResolution": "Node",
     "esModuleInterop": true,
     "outDir": "dist",
     "strict": true,
     "declaration": true,
-    "types": ["node"]
+    "types": [
+      "node"
+    ]
   },
-  "include": ["src"]
+  "include": [
+    "src"
+  ]
 }

test/index.test.ts

@@ -14,6 +14,7 @@ import {
   resolveLockfile,
   findWorkspaceDir,
 } from "../src";
+import { readFile } from "node:fs/promises";
 
 const fixtureDir = resolve(dirname(fileURLToPath(import.meta.url)), "fixture");
 
@@ -90,6 +91,19 @@ describe("package.json", () => {
       "string",
     );
   });
+
+  it("styles are preserved", async () => {
+    const originalContent = await readFile(rFixture("package.json"), "utf8");
+    await writePackageJSON(
+      rFixture("package.json") + ".tmp",
+      await readPackageJSON(rFixture("package.json")),
+    );
+    const newContent = await readFile(
+      rFixture("package.json") + ".tmp",
+      "utf8",
+    );
+    expect(newContent).toBe(originalContent);
+  });
 });
 
 describe("tsconfig.json", () => {
@@ -112,6 +126,19 @@ describe("tsconfig.json", () => {
     // TODO: type check this file.
     // expectTypeOf(options.maxNodeModuleJsDepth).toEqualTypeOf<number | undefined>()
   });
+
+  it("styles are preserved", async () => {
+    const originalContent = await readFile(rFixture("tsconfig.json"), "utf8");
+    await writeTSConfig(
+      rFixture("tsconfig.json") + ".tmp",
+      await readTSConfig(rFixture("tsconfig.json")),
+    );
+    const newContent = await readFile(
+      rFixture("tsconfig.json") + ".tmp",
+      "utf8",
+    );
+    expect(newContent).toBe(originalContent.replace(/\s*\/\/\s*.+/g, ""));
+  });
 });
 
 describe("resolveLockfile", () => {