Add support for d.ts declaration generation

Author: rdmurphy

package.json

@@ -13,10 +13,9 @@
     "types"
   ],
   "scripts": {
-    "build": "npm run -s build:babel && npm run -s build:self && npm run build:types",
-    "build:babel": "babel-node --extensions \".ts\" src/cli.ts \"src/{cli,index}.ts\" --target=8 --output=dist --compress",
-    "build:self": "node dist/cli.js \"src/{cli,index}.ts\" --target=8 --output=dist --compress",
-    "build:types": "tsc --emitDeclarationOnly --outdir types --declaration --allowSyntheticDefaultImports src/{cli,index}.ts",
+    "build": "npm run -s build:babel && npm run -s build:self",
+    "build:babel": "babel-node --extensions \".ts\" src/cli.ts \"src/{cli,index}.ts\" --target=8 --output=dist --compress --types=types",
+    "build:self": "node dist/cli.js \"src/{cli,index}.ts\" --target=8 --output=dist --compress --types=types",
     "prerelease": "npm run build",
     "release": "np",
     "test": "echo \"Error: no test specified\" && exit 0"

src/cli.ts

@@ -21,8 +21,9 @@ async function main(argv_: string[]) {
   const outputDir = args.output;
   const compress = args.compress;
   const nodeTarget = args.target;
+  const typesDir = args.types;
 
-  await bundler({ compress, input, nodeTarget, outputDir });
+  await bundler({ compress, input, nodeTarget, outputDir, typesDir });
 }
 
 main(process.argv).catch(console.error);

src/index.ts

@@ -1,4 +1,5 @@
 // native
+import { spawn } from 'child_process';
 import { basename, parse, resolve } from 'path';
 
 // packages
@@ -124,29 +125,56 @@ async function createRollupConfig({
   return { inputOptions, outputOptions };
 }
 
+function createTypes({ input, output }: { input: string; output: string }) {
+  return new Promise((fulfill, reject) => {
+    const child = spawn('tsc', [
+      '--declaration',
+      '--emitDeclarationOnly',
+      '--allowSyntheticDefaultImports',
+      '--declarationDir',
+      output,
+      input,
+    ]);
+
+    child.on('error', reject);
+    child.on('exit', fulfill);
+  });
+}
+
 interface BundlerOptions {
   compress: boolean;
   input: string;
   nodeTarget: string;
   outputDir: string;
+  typesDir?: string;
 }
 
 export async function bundler({
   compress,
   input,
   nodeTarget,
   outputDir,
+  typesDir,
 }: BundlerOptions) {
+  // the current working directory
   const cwd = process.cwd();
 
+  // if a custom typesDir was not passed, use outputDir
+  typesDir = typesDir || outputDir;
+
+  // get the contents of package.json
   const pkg = await getConfig(cwd);
 
+  // pull out all of the dependencies to flag externals
   const pkgDependencies = Object.keys(pkg.dependencies || {});
 
+  // find all the input TypeScript files
   const inputs = await glob(input, { absolute: true });
 
+  // if we have more than one input, flag this as a multi-input run
   const withMultipleInputs = inputs.length > 1;
 
+  // loop thorugh the inputs, creating a rollup configuraion for each one
   for (let idx = 0; idx < inputs.length; idx++) {
     const input = inputs[idx];
 
@@ -167,7 +195,10 @@ export async function bundler({
     const bundle = await rollup(inputOptions);
 
     for (let idx = 0; idx < outputOptions.length; idx++) {
-      await bundle.write(outputOptions[idx]);
+      const output = outputOptions[idx];
+
+      await bundle.write(output);
+      await createTypes({ input, output: typesDir });
     }
   }
 }