feature/ts-support: Add new loader

README.md

@@ -109,6 +109,8 @@ It will check these files and return config file if found it.
 - `.your-applicationrc.yml`
 - `.your-applicationrc.yaml`
 - `.your-applicationrc.js`
+- `.your-applicationrc.cjs`
+- `.your-applicationrc.ts`
 - [optional] `package.json`
   - if `packageJSON` option is enabled
 

package.json

@@ -60,7 +60,8 @@
     "debug": "^4.3.4",
     "js-yaml": "^4.1.0",
     "json5": "^2.2.1",
-    "require-from-string": "^2.0.2"
+    "require-from-string": "^2.0.2",
+    "typescript": "^4.8.4"
   },
   "devDependencies": {
     "@types/mocha": "^9.1.0",
@@ -70,7 +71,6 @@
     "mocha": "^9.2.2",
     "prettier": "^2.6.2",
     "ts-node": "^10.7.0",
-    "ts-node-test-register": "^10.0.0",
-    "typescript": "^4.6.3"
+    "ts-node-test-register": "^10.0.0"
   }
 }

src/rc-config-loader.ts

@@ -5,11 +5,13 @@ import path from "path";
 import fs from "fs";
 import requireFromString from "require-from-string";
 import JSON5 from "json5";
+import ts from "typescript";
 
 const debug = require("debug")("rc-config-loader");
 const defaultLoaderByExt = {
     ".cjs": loadJSConfigFile,
     ".js": loadJSConfigFile,
+    ".ts": loadTSConfigFile,
     ".json": loadJSONConfigFile,
     ".yaml": loadYAMLConfigFile,
     ".yml": loadYAMLConfigFile
@@ -19,7 +21,7 @@ const defaultOptions = {
     // does look for `package.json`
     packageJSON: false,
     // treat default(no ext file) as some extension
-    defaultExtension: [".json", ".yaml", ".yml", ".js", ".cjs"],
+    defaultExtension: [".json", ".yaml", ".yml", ".ts", ".js", ".cjs"],
     cwd: process.cwd()
 };
 
@@ -192,6 +194,26 @@ function loadJSConfigFile(filePath: string, suppress: boolean) {
     }
 }
 
+function loadTSConfigFile(filePath: string, supperes: boolean) {
+    debug(`Loading TypeScript config file: ${filePath}`);
+
+    try {
+        const code = fs.readFileSync(filePath, "utf-8");
+        const content = ts.transpile(code, {
+            module: ts.ModuleKind.Node16,
+            target: ts.ScriptTarget.ES5
+        });
+
+        return requireFromString(content, filePath).default;
+    } catch (error: any) {
+        debug(`Error reading TypeScript file: ${filePath}`);
+        if (!supperes) {
+            error.message = `Cannot read config file: ${filePath}\nError: ${error.message}`;
+            throw error;
+        }
+    }
+}
+
 function loadJSONConfigFile(filePath: string, suppress: boolean) {
     debug(`Loading JSON config file: ${filePath}`);
 

test/fixtures/.tsrc.ts

@@ -0,0 +1,7 @@
+type Config = {
+    foo: "foo";
+};
+
+export default <Config>{
+    foo: "foo"
+};

test/rc-config-loader-test.ts

@@ -43,6 +43,16 @@ describe("rc-config-loader", () => {
         assert.deepStrictEqual(config, { bar: "bar" });
     });
 
+    it("should read ts config in current directory", () => {
+        const results = rcFile("ts", { cwd: path.join(__dirname, "fixtures") });
+
+        if (!results) {
+            throw new Error("not found");
+        }
+        const { config } = results;
+        assert.deepStrictEqual(config, { foo: "foo" });
+    });
+
     it("should read cjs config in current directory", () => {
         const results = rcFile("baz", { cwd: path.join(__dirname, "fixtures") });
         if (!results) {