add begin and end option

docs/assets/example/thumbnail.js

@@ -1,3 +1,7 @@
+if (window.lastThumbnail) {
+    window.lastThumbnail.destroy();
+}
+
 var $popups = document.querySelector('.popups');
 var $popinner = document.querySelector('.popinner');
 var $artplayer = document.querySelector('.artplayer-app');
@@ -10,39 +14,43 @@ var thumbnail = new ArtplayerToolThumbnail({
     width: 160, // 宽度
     height: 90, // 高度
     column: 10, // 列数
+    begin: 0, // 开始
+    end: NaN, // 结束
 });
 
-thumbnail.on('file', function(file) {
+window.lastThumbnail = thumbnail;
+
+thumbnail.on('file', function (file) {
     console.log('Read video successfully: ' + file.name);
 });
 
-thumbnail.on('video', function(video) {
+thumbnail.on('video', function (video) {
     console.log('Video size: ' + video.videoWidth + ' x ' + video.videoHeight);
     console.log('Video duration: ' + video.duration + 's');
     thumbnail.start();
 });
 
-thumbnail.on('canvas', function(canvas) {
+thumbnail.on('canvas', function (canvas) {
     console.log('Build canvas successfully');
     console.log('Canvas size: ' + canvas.width + ' x ' + canvas.height);
     console.log('Preview density: ' + thumbnail.density + ' p/s');
 });
 
-thumbnail.on('update', function(url, percentage) {
+thumbnail.on('update', function (url, percentage) {
     console.log('Processing: ' + Math.floor(percentage.toFixed(2) * 100) + '%');
     $popups.style.display = 'flex';
     $popinner.style.backgroundImage = 'url(' + url + ')';
 });
 
-thumbnail.on('download', function(name) {
+thumbnail.on('download', function (name) {
     console.log('Start download preview: ' + name);
 });
 
-thumbnail.on('done', function() {
+thumbnail.on('done', function () {
     $popups.style.display = 'none';
     thumbnail.download();
     console.log('Build preview image complete');
-    Artplayer.instances.forEach(function(art) {
+    Artplayer.instances.forEach(function (art) {
         art.destroy(true);
     });