add travis yml

.travis.yml

@@ -0,0 +1,15 @@
+language: node_js
+
+node_js:
+  - '12.16.1'
+
+install:
+  - npm install
+
+script:
+  - npm test
+  - npm run build
+
+cache:
+  directories:
+    - node_modules

src/pagination.ts

@@ -10,16 +10,9 @@ import { range, rewind } from './utils/utils';
  * @param total Total bullets. Same as amount of slides.
  */
 export function mapActiveIndex(index: number, center: number, total: number) {
-  return index - Math.max(index - center, 0) + Math.max(index - (total - 1 - center), 0);
+  return index - Math.max(index - center, 0) + Math.max(index - (-1 + total - center), 0);
 }
 
-/**
- * Figure out if given bullet element index is edge.
- *
- * @param index Current bullet element index.
- */
-export function isEdgeBullet(index: number) {}
-
 export class Pagination {
   private ref: HTMLElement;
   private currentIndex: number = 0;

src/virchual.ts

@@ -1,8 +1,8 @@
-import { Pagination } from './pagination';
 import './css/styles.css';
-
 import { Drag } from './drag';
+import { Pagination } from './pagination';
 import { Slide } from './slide';
+import { Sign } from './types';
 import { assert } from './utils/error';
 import { Event } from './utils/event';
 import { slidingWindow } from './utils/sliding-window';
@@ -87,6 +87,9 @@ export class Virchual {
     this.pagination.render();
   }
 
+  /**
+   * Mount components.
+   */
   mount() {
     this.event.emit('mounted');
 
@@ -116,12 +119,18 @@ export class Virchual {
     this.event.off(events, elm);
   }
 
+  /**
+   * Go to previous slide.
+   */
   prev() {
     console.debug('[Controls] Previous');
 
     this.go('prev');
   }
 
+  /**
+   * Go to next slide.
+   */
   next() {
     console.debug('[Controls] Next');
 
@@ -135,7 +144,7 @@ export class Virchual {
       this.isBusy = false;
     });
 
-    const sign = direction === 'prev' ? -1 : +1;
+    const sign: Sign = direction === 'prev' ? -1 : +1;
 
     this.currentIndex = rewind(this.currentIndex + sign * 1, this.slides.length - 1);