1. added typescript badge

2. added typescript usage notice in readme,  #19

package.json

@@ -8,7 +8,7 @@
   "scripts": {
     "dev": "npm run build:dir",
     "build": "npm run lint && npm run test && npm run build:dir",
-    "build:dir": "npm run clean:builddir && rollup -c --environment format:cjs && rollup -c --environment format:es",
+    "build:dir": "npm run clean:builddir && rollup -c rollup.config.ts",
     "clean:builddir": "rimraf dist/*",
     "postpublish": "./post-publish2npm.sh",
     "test": "jest --coverage",

readme.md

@@ -5,6 +5,9 @@
   <a href="https://travis-ci.org/evecalm/truncate-html">
     <img src="https://travis-ci.org/evecalm/truncate-html.svg?branch=master" alt="Travis CI">
   </a>
+  <a href="#readme">
+    <img src="https://badges.frapsoft.com/typescript/code/typescript.svg?v=101" alt="code with typescript" height="20">
+  </a>
   <a href="#readme">
     <img src="https://badge.fury.io/js/truncate-html.svg" alt="npm version" height="18">
   </a>
@@ -108,6 +111,10 @@ truncate($)
 
 ## Notice
 
+### Typescript support
+
+This lib is written with typescript and has a defination file along with it. You may need to update your `tsconfig.json` by adding `"esModuleInterop": true` to the `compilerOptions` if you encounter some typing errors, see #19.
+
 ### About final string length
 
 If the html string content's length is shorter than `options.length`, then no ellipsis will be appended to the final html string. If longer, then the final string length will be `options.length` + `options.ellipsis`. And if you set `reserveLastWord` to true of none zero number, the final string will be various.

rollup.config.ts

@@ -0,0 +1,34 @@
+import buble from 'rollup-plugin-buble'
+import typescript from 'rollup-plugin-typescript2'
+
+const pkg = require('./package.json')
+
+function getConfig (type) {
+  return {
+    input: 'src/truncate.ts',
+    output: {
+      name: 'truncate-html',
+      banner: `/*!
+ * trancate-html v${pkg.version}
+ * Copyright© ${new Date().getFullYear()} Saiya ${pkg.homepage}
+ */`,
+      format: type,
+      file: `dist/truncate.${type}.js`
+    },
+    plugins: [
+      typescript({
+        tsconfigOverride: {
+          compilerOptions: { module: 'esnext' }
+        },
+        typescript: require('typescript')
+      }),
+      buble()
+    ],
+    external: ['cheerio']
+  }
+}
+
+export default [
+  getConfig('cjs'),
+  getConfig('es')
+]