LiteList

Virtual list with low DOM overhead

About

LiteList is a small library providing an efficient, scrollable view backed by a list containing potentially thousands of entries.

Installation

npm install litelist or grab the source. Bower is still tbd.

Couple of notes on that topic:

• For desktop browser support - litelist.js or litelist.min.js will do. No other dependencies are needed.
• For mobile support - because mobile browsers don't consistently provide scroll events, a scrolling module borrowed heavily from ariya/kinetic is bundled in with the library. If used, you will either need to create a custom build with Tween.JS or reference it in your markup. Additional modules for mobile scrolling include:
  • A lightweight scrolling implementation borrowed heavily from ariya/kinetic (bundled)
  • Tween.JS - for smoother scrolling
  • raf.js - Yet another requestAnimationFrame polyfill (bundled).

Usage

Initialization

Vanilla Javascript

var liteList = LiteList({
    itemWidth       : Optional - width of each item.  If not provide one item per row is assumed
    itemHeight      : Required - height of each item.
    margin          : Optional - margin/gutters for the items.  Defaults to: { x: 0, y: 0 };
    scrollView      : Required - query selector for the scrollable container
    itemsContainer  : Optional - query selector container of the items.  Defaults to the first child of scrollView

    // The next two are required for a vanilla javascript implementation.  ListList was written to work
    // with the Rivets library which provides this functionality as well.  In that case, it is optional.
    itemTemplate    : Required - DOM node that will be cloned as a template for each item.
    dataSource      : Required - Implementation of the dataSource contract (see below for more details).
});

Rivets

LiteList was written to work with the excellent Rivets library. Rivets will do the heavy lifting for the data binding and managing the DOM. For a more thorough example of how to implement this using Rivets, see the Rivets demo.

Rivets is not in the bundled libraries it can be included separately when needed or you can create a custom bundle.

var rvLiteList = new LiteList.RivetsLiteList({
    itemWidth       : Optional - width of each item.  If not provide one item per row is assumed
    itemHeight      : Required - height of each item.
    margin          : Optional - margin/gutters for the items.  Defaults to: { x: 0, y: 0 };
    scrollView      : Required - query selector for the scrollable container
    itemsContainer  : Optional - query selector container of the items.  Defaults to the first child of scrollView
});

dataSource

dataSource is an object implementing a sync method and optionally, bind and unbind. For a more thorough exammple of how to implement this interface see vanilla demo

dataSource: {
    bind:   function(id, el) {...},
    sync:   function(id, el, itemIdx, item) {},
    unbind: function(id, el) {}
}

bind: Optional, but recommended. Called once when a template is realized and appended to itemsContainer. A typical implementation would be to obtain a reference (mapped to id) to any node that will need to be updated for faster access during sync. You would also register any event handlers here, although it may be more appropriate to allow the events to bubble up to the items container and handle them there...

• id: unique id of the realized template
• el: the actual dom element

sync: Called each time the view needs updating.

• id: unique id of the realized template
• el: the actual dom element
• itemIdx: index of the item in the item array
• item: the actual item to be rendered into el

unbind: Optional but recommended/required if storing references in bind. Called once when a view node is removed from the DOM.

Development

Grunt with browserify via grunt-browserify is the build system for LiteList. Once you have cloned the repo and have nodejs and Grunt installed run:

npm install .

from the projects root folder. Once that is done, you will be able to run various tasks using grunt:

• grunt: runs a dev server on port 9001, then watches for changes.
• grunt build: rebuilds contents of the dist folder

For more detail on which tasks are run and the targets available, take a look at Gruntfile.js

To Dos

While the basic implementation if functional and seems to work well on various mobile browsers, additional testing still needs to occur (both performance and functional). It is very likely that as implementation proceeds the exposed API and internal implementation will change significantly.

• Verify browser compatibility and document any shims needed for older browsers
• Provide a simple, performant mechanism for lazy loading of the list.
• Expose generated scroll events from scroller (for mobile use case)
• Expose better ways to populate and maintain the list of items
• Support a visible scrollbar for mobile browsers
• more...

Contributing

Contributions of any kind (feature request, bug reports/fixes, pull requests, complaints, comments, 'why don't you just use x module instead') are all welcome.

License

MIT. See LICENSE.txt in this directory.