Brightcove Player Sample: Trigger Rewind with a Custom Event

Product(s)
Video Cloud
Brightcove Player
Role(s)
Player Developer
Topic(s)
Code Samples
Events

In this topic, you will learn how to implement a rewind button by dispatching and listening for a custom event.

Overview

Even though the Brightcove player provides a number of out-of-the-box events, you may want to use your own custom events to decouple and eliminate dependencies between DOM objects and event listeners. This event-driven model is an architectural choice that you may want to consider.

This sample adds a back button to the control bar. When the user clicks the back button, a custom event is triggered along with the amount of time to rewind. The custom event listener finds the current video position and rewinds the video.

Player example

Start video playback. Then click on the back button:

rewind video button

You should see that video playback goes back 5 seconds.

See the Pen 18150-trigger-rewind-custom-event by Brightcove Learning Services (@bcls1969) on CodePen.

View the source code.

Using the CodePen

Here are some tips to effectively use the above CodePen:

  • Toggle the actual display of the player by clicking the Result button.
  • Click the HTML/CSS/JS buttons to display ONE of the code types.
  • Later in this document the logic, flow and styling used in the application will be discussed in the Player/HTML configuration, Application flow and Application styling sections. The best way to follow along with the information in those sections is to:
    1. Click the EDIT ON CODEPEN button in the CodePen and have the code available in one browser/browser tab.
    2. In CodePen, adjust what code you want displayed. You can change the width of different code sections within CodePen.
    3. View the Player/HTML configuration, Application flow and/or Application styling sections in another browser/browser tab. You will now be able to follow the code explanations and at the same time view the code.

Development sequence

Here is the recommended development sequence:

  1. Use the In-Page embed player implementation to test the functionality of your player, plugin and CSS (if CSS is needed)
  2. Put the plugin's JavaScript and CSS into separate files for local testing
  3. Deploy the plugin code and CSS to your server once you have worked out any errors
  4. Use Studio to add the plugin and CSS to your player
  5. Replace the In-Page embed player implementation if you determine that the iframe implementation is a better fit (detailed in next section)

For details about these steps, review the Quick Start: Plugin Development guide.

iframe or In-Page embed

When developing enhancements for the Brightcove player you will need to decide if the code is a best fit for the iframe or In-Page embed implementation. The best practice recommendation is to build a plugin for use with an iframe implementation. The advantages of using the iframe player are:

  • No collisions with existing JavaScript and/or CSS
  • Automatically responsive
  • The iframe eases use in social media apps (or whenever the video will need to "travel" into other apps)

Although integrating the In-Page embed player can be more complex, there are times when you will plan your code around that implementation. To generalize, this approach is best when the containing page needs to communicate to the player. Specifically, here are some examples:

  • Code in the containing page needs to listen for and act on player events
  • The player uses styles from the containing page
  • The iframe will cause app logic to fail, like a redirect from the containing page

Even if your final implementation does not use the iframe code, you can still use the In-Page embed code with a plugin for your JavaScript and a separate file for your CSS. This encapsulates your logic so that you can easily use it in multiple players.

API/Plugin resources used

API Methods API Events
spacer.appendChild() trigger
currentTime() on

Player/HTML configuration

This section details any special configuration needed during player creation. In addition, other HTML elements that must be added to the page, beyond the in-page embed player implementation code, are described.

Player configuration

No special configuration is required for the Brightcove Player you create for this sample.

Other HTML

Remember to add the id attribute to the video-js tag in the player embed code.

<video-js id="myPlayerID"
...

Application flow

The basic logic behind this application is:

  • Create a new element in the DOM for the rewind button.
  • Add the rewind button to the player control bar.
  • Listen for when a user clicks on the rewind button. When clicked, trigger your custom event with data.
  • Listen for the custom event with data and rewind video playback based on the data defined.

Add elements to the DOM

Find the code which is labeled:

// +++ Add elements to the DOM +++

Create a new <div> element in the DOM and assign an id attribute with a value of backButton. Create a new <img> element in the DOM and assign the src attribute with the URL to your rewind button.

Add rewind button to the control bar

Find the code which is labeled:

// +++ Add rewind button to the control bar +++

Get the spacer element in the control bar, and add the rewind button elements to it.

Listen for the rewind button

Find the code which is labeled:

// +++ Listen for the rewind button +++

To the backButton element, add a listener for the onclick event. When clicked, trigger your custom event with data.

Listen for rewind event

Find the code which is labeled:

// +++ Listen for rewind event +++

Listen for your custom event with data. When triggered, rewind video playback based on the rewindAmt defined in the code..

Application styling

CSS is used to size the player and to position and size the rewind button in the control bar.

Plugin code

Normally when converting the JavaScript into a Brightcove Player plugin nominal changes are needed. One required change is to replace the standard use of the ready() method with the code that defines a plugin.

Here is the very commonly used start to JavaScript code that will work with the player:

videojs.getPlayer('myPlayerID').ready(function() {
  var myPlayer = this;
  ...
});

You will change the first line to use the standard syntax to start a Brightcove Player plugin:

videojs.registerPlugin('pluginName', function(options) {
  var myPlayer = this;
  ...
});

As mentioned earlier, you can see the plugin's JavaScript code in this document's corresponding GitHub repo: custom-event.js.

Understanding Custom events

Custom events allow you to decouple and eliminate dependencies between DOM objects and event listeners, creating an event-driven architectural model.

Dispatch

To dispatch a custom event, use the trigger() method as follows:

// trigger a custom event
myPlayer.trigger('eventName');
or
// trigger a custom event with data
myPlayer.trigger('eventName', {data: 'some data'});

For details about dispatching custom events, see the Player API index.

In this sample, the code does the following:

  • Dispatches a custom event, named rewind
  • Sends a data object with a name of amount and a value of 5 - You'll see in the JavaScript code where this value is set
// trigger a custom event with data
myPlayer.trigger('rewind', {'amount': rewindAmount});

Listen

To listen for a custom event, you can use the on() method as follows:

// listen for a custom event
player.on('eventName', function(evt){});
or
// listen for a custom event with data
player.on('eventName', function(evt,data){});

You can also use the one() method if you want the event listener to be triggered only once and then removed. For details about listening for events, see the Player API index.

In this sample, the code does the following:

  • Listens for a custom event, named rewind
  • Passes the event and data objects into a function
// listen for a custom event with data
 myPlayer.on('rewind',function(evt,data){
});

When you display the event and data objects in the console, it should look similar to this:

Custom event data
Custom event data