Home > Articles > Mobile Application Development & Programming

  • Print
  • + Share This
This chapter is from the book

This chapter is from the book

Cordova Initialization

Now let’s take the previous example application and add some Cordova-specific stuff to it.

Even though the Cordova container exposes native APIs to the web application running within it, in general (there are a few exceptions) those APIs are not available until the plugin that exposes the API has been added to the project. Additionally, the Cordova container has to do some prep work before any of its APIs can be utilized. To make it easy for developers to know when they can start using APIs exposed by the Cordova container, Cordova fires a specific event, the deviceready event, once it has finished its initialization and it’s ready to go. Any application processing that requires the use of the Cordova APIs should be executed by the application only after it has received its notification that the Cordova container is available through the deviceready event.

The Hello World #2 application shown in Listing 2.2 has been updated to include code that uses a deviceready event listener to determine when the Cordova container application has completed its initialization. In this simple example, the application just displays an alert dialog when the event fires.

Listing 2.2 Hello World #2 Application

<!DOCTYPE html>
<html>
<head>
   <title>Hello World #2</title>
   <meta charset="utf-8" />
   <meta name="format-detection" content="telephone=no" />
   <meta name="viewport" content="user-scalable=no, initial-scale=1,
     maximum-scale=1, minimum-scale=1, width=device-width,
     height=device-height" />
   <script src="cordova.js"></script>
   <script>

   function onBodyLoad() {
     console.log("Entering onBodyLoad");
     alert("Body Load");
     document.addEventListener("deviceready", onDeviceReady, false);
   }

   function onDeviceReady() {
     console.log("Cordova is ready");
     navigator.notification.alert("Cordova is ready!");
   }

  </script>
</head>
<body onload="onBodyLoad()">
  <h1>Hello World #2</h1>
  <p>This is a sample Cordova application.</p> 
</body> 
</html>

On the iPhone simulator, the application will display the screen shown in Figure 2.3.

Figure 2.3

Figure 2.3 Hello World #2 Application Running on an iOS Simulator

Let’s take a look at the sample application as there’s a lot of new stuff in this example.

Within the <head> section of the web page are a few new entries, some meta tags that describe the content type for the application, and some other settings. For the most part, I pulled these meta tags from the default Cordova HelloCordova application described later in the chapter.

The charset tag identifies the character encoding used for the HTML document. What I’ve shown here is the default option; you would change this only if you were using a different character set for the HTML page.

<meta charset="utf-8" />

The next tag disables the embedded web browser’s automatic processing of telephone numbers. With this option disabled, as shown below, the browser won’t automatically turn phone numbers on the page into clickable links. You would need to change telephone=no to telephone=yes to enable this option.

<meta name="format-detection" content="telephone=no" />

Honestly, I’m really not sure why the Cordova team did this in their sample application; you would probably assume the user was running the application on a smartphone and would want phone numbers to be automatically enabled as links.

The viewport settings shown in the following tell the embedded web browser rendering the content how much of the available screen real estate should be used for the application and how to scale the content on the screen:

<meta name="viewport" content="user-scalable=no, initial-scale=1,
  maximum-scale=1, minimum-scale=1, width=device-width,
  height=device-height" />

In this case, the HTML page is configured to use the maximum height and width of the screen (through the width=device-width and height=device-height attributes) and to scale the content at 100% and not allow the user to change that in any way (through the initial-scale=1, maximum-scale=1, and user-scalable=no attributes).

There’s also a new script tag in the code that loads the Cordova JavaScript library:

<script src="cordova.js"></script>

This loads the core Cordova API library and makes any core Cordova APIs available to the program. This file is also responsible for loading and initializing all of the plugins you have added to your Cordova application. You don’t have to add the cordova.js file to your project; this is done for you automatically by the Cordova CLI (described in Chapter 4, “Using the Cordova Command-Line Interfaces”), but you do need to add this reference to your application.

To set up the deviceready event listener we need for Cordova, the application adds an onload event function to the application’s body tag using the following:

<body onload="onBodyLoad()">

Within the onBodyLoad function, the code registers an event listener that instructs the application to call the onDeviceReady function when the Cordova container is ready, when the Cordova application container has finished its initialization routines and fired its deviceready event:

function onBodyLoad() {
  document.addEventListener("deviceready", onDeviceReady, false);
}

In this example application the onDeviceReady function simply displays a Cordova alert dialog (which is different from a JavaScript alert dialog) letting the user know everything’s OK:

navigator.notification.alert("Cordova is ready!")

In production applications this function could update the UI with content created through API calls or do whatever other processing is required by the application. (You’ll see an example of this in Listing 2.4.)

One of the things I do during testing is use the web browser console to display status messages as the application runs using code similar to the following:

console.log("Entering onBodyLoad");

I’ll show you how this works in Chapter 5, “The Mechanics of Cordova Development.”

In the onBodyLoad function, I also make sure to make a call to the JavaScript alert function so I can easily tell that the onload event has fired:

alert("Body Load");

As I mentioned earlier, the Cordova container fails silently when it encounters an error with the web application’s source code. So, if I have this alert in the code and it doesn’t fire, I know very quickly (in the very first code the application executes) that something is wrong with the application.

In the deviceready event handler, I always add a call to navigator.notification.alert as shown in the example code. This allows me to confirm visually that the deviceready event has actually fired, plus it allows me to confirm that the Cordova Dialogs plugin has been added to the project and that any other debug alerts I put into the code will be operational. I use the Cordova alert instead of the JavaScript alert because it’s better looking (I can set the title of the dialog, for example, although I didn’t do that here); it also gives me access to callback functions I can use to perform extra steps when something interesting happens.

Remember, most of the Cordova APIs have been removed from the container and implemented as plugins. So, to utilize the Cordova alert method, you must add the Dialogs plugin to your application by opening a terminal window to your Cordova project folder and issuing the following command:

cordova plugin add org.apache.cordova.dialogs

You’ll learn all about how to use the cordova command in Chapter 4. You’ll learn more about the Dialogs plugin in Chapter 14, “Working with the Cordova APIs.”

The deviceready event will fire when the Cordova container finishes initializing, but it will also fire any time a new deviceready event listener is added by the application. Listing 2.3 shows this in action.

Listing 2.3 Hello World #3 Application

<!DOCTYPE html>
<html>
<head>
<title>Hello World #3</title>
<meta charset="utf-8" />
<meta name="format-detection" content="telephone=no" />
<meta name="viewport" content="user-scalable=no, initial-scale=1,
  maximum-scale=1, minimum-scale=1, width=device-width,
  height=device-height" />
<script src="cordova.js"></script>
<script>

  function onBodyLoad() {
    console.log("Entering onBodyLoad");
    alert("Body Load");
    document.addEventListener("deviceready", onDeviceReady, false);
  }

  function onDeviceReady() {
    console.log("Entering onDeviceReady");
    navigator.notification.alert("Cordova is ready!");
  }

  function addSecondDeviceReadyListener() {
    console.log("Entering addSecondDeviceReadyListener");
    document.addEventListener("deviceready", someOtherFunction, false);
  }

  function someOtherFunction() {
    console.log("Entering someOtherFunction");
    navigator.notification.alert("Second deviceready Function Fired.");
  }

 </script>
</head>
<body onload="onBodyLoad()">
  <h1>Hello World #3</h1>
  <p>This is a sample Cordova application.</p>
  <button onclick="addSecondDeviceReadyListener()">Add deviceready Event Listener</ button>
</body>
</html>

In this example, I’ve added a button to the application’s main page. When the button is tapped, an additional deviceready event listener is defined, and then the callback function for the new listener is immediately executed by the Cordova container. In this case, the onDeviceReady function executes once the container completes its initialization, and then the someOtherFunction function executes only after the second deviceready event listener has been added.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020