add typescript compilation mechanism

.eslintrc.yaml

@@ -1,7 +0,0 @@
-env:
-  es6: true
-  node: true
-extends: 'eslint:recommended'
-parserOptions:
-  ecmaVersion: 2017
-  sourceType: module

package.json

@@ -10,9 +10,8 @@
 		"watcher"
 	],
 	"main": "./dist/CheapWatch.cjs.js",
-	"module": "./CheapWatch.js",
+	"module": "./dist/CheapWatch.es.js",
 	"files": [
-		"CheapWatch.js",
 		"dist"
 	],
 	"engines": {
@@ -29,12 +28,16 @@
 	},
 	"homepage": "https://conduitry.io/cheap-watch",
 	"devDependencies": {
-		"rollup": "*"
+		"rollup": "*",
+		"typescript": "*",
+		"@types/node": "*"
 	},
 	"scripts": {
-		"build": "rollup -c",
+		"build": "tsc && rollup -c",
+		"dev": "rollup -cw",
+		"prepare": "npm run build",
+		"prepublishOnly": "npm test",
 		"pretest": "npm run build",
-		"test": "node test.js",
+		"test": "node test.js"
-		"prepublishOnly": "npm test"
 	}
 }

rollup.config.js

@@ -1,6 +1,43 @@
+let transform;
+
+if (process.env.ROLLUP_WATCH === 'true') {
+	const { transpileModule } = require('typescript');
+	const tsconfig = require('./tsconfig.json');
+	transform = (code, id) => {
+		if (id.endsWith('.ts')) {
+			const { outputText, sourceMapText } = transpileModule(code, tsconfig);
+			return { code: outputText, map: JSON.parse(sourceMapText) };
+		}
+	};
+} else {
+	const { readFile, unlink } = require('fs');
+	const { promisify } = require('util');
+	transform = async (code, id) => {
+		if (id.endsWith('.ts')) {
+			id = id.slice(0, -2) + 'js';
+			const [js, map] = await Promise.all(
+				[id, id + '.map'].map(async path => {
+					const data = await promisify(readFile)(path);
+					unlink(path, () => null);
+					return data.toString();
+				}),
+			);
+			return { code: js, map: JSON.parse(map) };
+		}
+	};
+}
+
 export default {
-	input: './CheapWatch.js',
+	input: './src/CheapWatch',
-	external: name => /^[-a-z]+$/.test(name),
+	external: name => /^[a-z]/.test(name),
+	plugins: {
+		resolveId(importee, importer) {
+			if (/\/[^.]+$/.test(importee)) {
+				return this.resolveId(importee + '.ts', importer);
+			}
+		},
+		transform,
+	},
 	output: [
 		{
 			file: './dist/CheapWatch.cjs.js',
@@ -8,5 +45,6 @@ export default {
 			sourcemap: true,
 			interop: false,
 		},
+		{ file: './dist/CheapWatch.es.js', format: 'es', sourcemap: true },
 	],
 };

tsconfig.json

@@ -0,0 +1,11 @@
+{
+	"compilerOptions": {
+		"noImplicitAny": true,
+		"noImplicitThis": true,
+		"noUnusedLocals": true,
+		"removeComments": true,
+		"sourceMap": true,
+		"target": "esnext"
+	},
+	"include": ["src"]
+}