feat: Add support for TS config files

lib/eslint/eslint.js

@@ -94,6 +94,9 @@ const LintResultCache = require("../cli-engine/lint-result-cache");
 //------------------------------------------------------------------------------
 
 const FLAT_CONFIG_FILENAMES = [
+ "eslint.config.ts",
+ "eslint.config.mts",
+ "eslint.config.cts",
  "eslint.config.js",
  "eslint.config.mjs",
  "eslint.config.cjs"
@@ -269,6 +272,17 @@ function findFlatConfigFile(cwd) {
  );
 }
 
+/**
+ * Check if the file is a TypeScript file.
+ * @param {string} filePath The file path to check.
+ * @returns {boolean} `true` if the file is a TypeScript file, `false` if it's not.
+ */
+function isFileTS(filePath) {
+ const fileExtension = path.extname(filePath);
+
+ return fileExtension.endsWith("ts");
+}
+
 /**
  * Load the config array from the given filename.
  * @param {string} filePath The filename to load from.
@@ -312,7 +326,34 @@ async function loadFlatConfigFile(filePath) {
  delete require.cache[filePath];
  }
 
- const config = (await import(fileURL)).default;
+ const isTS = isFileTS(filePath);
+
+ if (isTS) {
+ const ts = (await import("typescript")).default;
+
+ const tsFileContent = await fs.readFile(filePath, "utf-8");
+
+ const tempFileName = `eslint.config.temp${path.extname(path.basename(filePath)).replace("t", "j")}`;
+
+ const outputPath = path.join(path.dirname(filePath), tempFileName);
+
+ const outputText = ts.transpile(tsFileContent,
+ { module: ts.ModuleKind.ESNext, moduleResolution: ts.ModuleResolutionKind.Node10, target: ts.ScriptTarget.ESNext });
+
+ try {
+ await fs.writeFile(outputPath, outputText, "utf-8");
+
+ const outputFileURL = pathToFileURL(outputPath);
+
+ const config = (await import(outputFileURL.href)).default;
+
+ return config;
+ } finally {
+ await fs.unlink(outputPath);
+ }
+ }
+
+ const config = (await import(fileURL.href)).default?.default ?? (await import(fileURL.href)).default;
 
  importedConfigFileModificationTime.set(filePath, mtime);
 

package.json

@@ -96,7 +96,8 @@
  "natural-compare": "^1.4.0",
  "optionator": "^0.9.3",
  "strip-ansi": "^6.0.1",
- "text-table": "^0.2.0"
+ "text-table": "^0.2.0",
+ "typescript": "^5.3.3"
  },
  "devDependencies": {
  "@babel/core": "^7.4.3",