Capture if the captions are displaying (#88)

src/js/video.js

@@ -27,7 +27,8 @@ function eventListener(video, ev) {
 
 	fireEvent(ev.type, video, {
 		progress: video.getProgress(),
-		duration: video.getDuration()
+		duration: video.getDuration(),
+		textTrackMode: video.getTrackMode()
 	});
 }
 
@@ -344,6 +345,10 @@ class Video {
 		return this.videoEl.duration ? parseInt(this.videoEl.duration, 10) : 0;
 	}
 
+	getTrackMode() {
+		return this.videoEl.textTracks && this.videoEl.textTracks[0] ? this.videoEl.textTracks[0].mode : undefined;
+	}
+
 	getAmountWatched(decimalPoints) {
 		const secondsWatched = this.amountWatched / 1000;
 		return decimalPoints !== undefined ? +(secondsWatched).toFixed(decimalPoints) : secondsWatched;

test/video.test.js

@@ -487,6 +487,26 @@ describe('Video', () => {
 
 	});
 
+	describe('#getTrackMode', () => {
+
+		it('should return the state of the video text track', () => {
+			const video = new Video(containerEl, { captionsUrl: 'http://localhost/a.vtt' });
+			video.addVideo();
+			setTimeout(() => {
+				video.getTrackMode().should.equal('disabled');
+			}, 100);
+		});
+
+		it('should return undefined if the video has no captions', () => {
+			const video = new Video(containerEl, {});
+			video.addVideo();
+			setTimeout(() => {
+				video.getTrackMode().should.equal(undefined);
+			}, 100);
+		});
+
+	});
+
 	describe('#getDuration', () => {
 		let video;