Firefox OS Help. Firefox for Android Help. Using files from web applications. Using the File API, which was added to the DOM in HTML5, it's now possible for web content to ask the user to select local files and then read the contents of those files.
This selection can be done by either using an HTML <input> element or by drag and drop. Using web workers - MDN Docs. Dedicated Web Workers provide a simple means for web content to run scripts in background threads.
Drag and drop. Firefox and other Mozilla applications support a number of features for handling drag and drop.
This allows the user to click and hold the mouse button down over an element, drag it to another location, and release the mouse button to drop the element there. A translucent representation of what is being dragged will follow the mouse pointer during the drag operation. The drop location may be a different application. Web sites, extensions, and XUL applications may make use of this functionality to customize what elements may be dragged, the drag feedback, as well as specify where elements may be dropped.
This section covers drag and drop in Firefox 3.5 (Gecko 1.9.1) and later. Drag and drop basics. DOM Storage. Summary.
IndexedDB. IndexedDB is an API for client-side storage of significant amounts of structured data, which also enables high performance searches of this data using indexes.
Using CSS transforms. By modifying the coordinate space, CSS transforms change the position and shape of the affected content without disrupting the normal document flow.
This guide provides an introduction to using transforms. CSS transforms are implemented using a set of CSS properties that let you apply affine linear transformations to HTML elements. CSS animations. CSS animations make it possible to animate transitions from one CSS style configuration to another.
Using CSS gradients. CSS gradients are new types of <image> added in the CSS3 Image Module.
Using CSS gradients lets you display smooth transitions between two or more specified colors. This lets you avoid using images for these effects, thereby reducing download time and bandwidth usage. In addition, because the gradient is generated by the browser, objects with gradients look better when zoomed, and you can adjust your layout much more flexibly. Browsers support two types of gradients: linear, defined with the linear-gradient() function, and radial, defined with radial-gradient(). Using Application Cache - MDN Docs. Introduction HTML5 provides an application caching mechanism that lets web-based applications run offline. Developers can use the Application Cache (AppCache) interface to specify resources that the browser should cache and make available to offline users.