W3C APIs

Tabris implements a subset of popular W3C standards. Besides providing web developers with familiar APIs, this also enables you to use libraries developed for a browser environment.

window object

In JavaScript there is always an object that represents the global scope. All global variables are members of this object. As in a web browser, this object is named window in Tabris.js. For example, the tabris object can be accessed either via tabris or window.tabris.

console object

As in the browser, messages can be logged to the developer console using the global console object:

console.log("A log message");
console.error("An error Message");
console.warn("A warning message");
console.info("An info message");
console.debug("A debug Message");

Calling console.error will also cause a message to pop up (even if the developer console is closed), but it won’t interrupt script execution.

Timer

Tabris supports the timer methods setTimeout, setInterval, clearTimeout and clearInterval. See window.

See W3C / MDN

XMLHttpRequest

Tabris supports the XMLHttpRequest to make HTTP request and to read resources that are part of the application.

See W3C / MDN

Tabris.js specifics:

• Only asynchronous requests are supported. Attempting a synchronous request will cause an error.
• When a relative URL is given, Tabris.js will interpret it as a path relative to the application’s package.json. This allows you to read static resources (files residing in your project folder).
• When using a custom built developer client, a relative URL may be used to access local files (bundled with the client as a resource) as well as those residing in the remote project folder (from which the code is loaded via HTTP). Local files take precedence.
• To enable access to SSL protected resources that use self signed certificates, use the UseStrictSSL preference in the config.xml. See the Cordova documentation.

To load static resources, working with URLs relative to the current module may be more convenient. In the case of a JSON file, this can be done simply by using the require method instead of XHR. For other types of files, use the __dirname variable, e.g. xhr.open("GET", __dirname + "/foo.txt");. You may also want to use the fetch module, which provides a more modern API than XHR.

Storage

Tabris supports the localStorage object, which allows storing simple key-value pairs.

See W3C / MDN

Tabris.js specifics:

• Currently the localStorage supports the methods setItem, getItem, removeItem, and clear.
• The sessionStorage is not supported, as it would serve no purpose in a non-browser environment.
• The storage event is currently not supported.

The localStorage is only meant to store relatively short strings. To store larger amounts of data it is recommended to use the cordova FileSystem plugin.

Canvas Context

The Canvas widget provides an HTML5 canvas compatible “2D Context” object. See Canvas.

See W3C / MDN