Rollup build (#311)

* replace gulp build with rollup

* bump version

* point main to es6 module

* revert change to test umd

* remove browserify

* update eslint config

* fix rollup error

* update readme

.eslintrc.js

@@ -1,5 +1,6 @@
 module.exports = {
   root: true,
+  ignorePatterns: ['*.js', '*.html', 'node_modules/*'],
   parser: '@typescript-eslint/parser',
   plugins: [
     '@typescript-eslint',

README.md

@@ -21,8 +21,8 @@ Or tinker with CountUp in [Stackblitz](https://stackblitz.com/edit/countup-types
 - **Highly customizeable** with a large range of options, you can even substitute numerals.
 - **Smart easing**: CountUp intelligently defers easing until it gets close enough to the end value for easing to be visually noticeable. Configureable in the [options](#options).
 - **Plugins** allow for alternate animations like the [Odometer plugin](https://www.npmjs.com/package/odometer_countup)
+
 ![Odomoeter plugin](./demo/images/odometer_plugin.gif)
-- **Separate bundles** for modern and legacy browsers, with and without the requestAnimationFrame polyfill. Choose `countUp.min.js` for modern browsers or `countUp.withPolyfill.min.js` for IE9 and older, and Opera mini.
 
 ## Usage:
 
@@ -143,7 +143,7 @@ countUp.handleScroll();
 
 Currently there's just one plugin, the **[Odometer Plugin](https://github.com/msoler75/odometer_countup.js)**.
 
-To use a plugin, use the plugin option:
+To use a plugin, you'll need to first install the plugin package. Then you can include it and use the plugin option. See each plugin's docs for more detailed info.
 ```js
 const countUp = new CountUp('targetId', 5234, {
   plugin: new Odometer({ duration: 2.3, lastDigitDelay: 0 }),
@@ -156,7 +156,7 @@ If you'd like to make your own plugin, see [the docs](#creating-animation-plugin
 
 ## Including CountUp
 
-CountUp is distributed as an ES6 module because it is the most standardized and most widely compatible module for browsers, though a UMD module is [also included](#umd-module).
+CountUp is distributed as an ES6 module because it is the most standardized and most widely compatible module for browsers, though a UMD module is [also included](#umd-module), along with a separate requestAnimationFrame polyfill (see below).
 
 For the examples below, first install CountUp. This will give you the latest:
 ```
@@ -206,6 +206,10 @@ var numAnim = new countUp.CountUp('myTarget', 2000);
 numAnim.start()
 ```
 
+### requestAnimationFrame polyfill
+
+You can include `dist/requestAnimationFrame.polyfill.js` if you want to support IE9 and older, and Opera mini.
+
 ---
 
 ## Contributing

dist/countUp.d.ts

@@ -49,7 +49,7 @@ export declare class CountUp {
      * Smart easing works by breaking the animation into 2 parts, the second part being the
      * smartEasingAmount and first part being the total amount minus the smartEasingAmount. It works
      * by disabling easing for the first part and enabling it on the second part. It is used if
-     * usingEasing is true and the total animation amount exceeds the smartEasingThreshold.
+     * useEasing is true and the total animation amount exceeds the smartEasingThreshold.
      */
     private determineDirectionAndSmartEasing;
     start(callback?: (args?: any) => any): void;

dist/countUp.js

@@ -15,7 +15,7 @@ var CountUp = /** @class */ (function () {
         var _this = this;
         this.endVal = endVal;
         this.options = options;
-        this.version = '2.6.0';
+        this.version = '2.6.1';
         this.defaults = {
             startVal: 0,
             decimalPlaces: 0,
@@ -177,7 +177,7 @@ var CountUp = /** @class */ (function () {
      * Smart easing works by breaking the animation into 2 parts, the second part being the
      * smartEasingAmount and first part being the total amount minus the smartEasingAmount. It works
      * by disabling easing for the first part and enabling it on the second part. It is used if
-     * usingEasing is true and the total animation amount exceeds the smartEasingThreshold.
+     * useEasing is true and the total animation amount exceeds the smartEasingThreshold.
      */
     CountUp.prototype.determineDirectionAndSmartEasing = function () {
         var end = (this.finalEndVal) ? this.finalEndVal : this.endVal;