Choreographer

Choreographer is a JavaScript library designed for orchestrating complex sequences of browser animations.

It sprouted from the development Randy's animation code, which sports numerous timed, sequential CSS transitions and animations. It became a big nuisance trying to dynamically coordinate all those animations using JavaScript, since JavaScript doesn't control CSS animations. When Promises and listening for transitionends became too messy, it became necessary to abstract away the coordination code into its own module. Thus, Choreographer!

Installation

Download the built file:

$ npm install choreographerjs

Documentation

Choreographer's raison d'être is to synchronize a long sequence of animations. It was designed to choreograph CSS animations, but should also work for JavaScript animations. It works by storing a map ("choreography") from times to (arrays of) animation functions. When the perform() method is invoked, the Choreographer loops through the keys of the map (which correspond to execution times) and creates a timeout that runs the stored animation functions at that time/key.

An example will make that more clear. Given this choreography

{
  0: [ fn1 ],
  300: [ fn2, fn3 ],
  600: [ fn4 ]
}

On invocation of Choreographer.perform(), three timeouts would be created:

setTimeout(function () { fn1(); }, 0);
setTimeout(function () { fn2(); fn3(); }, 300);
setTimeout(function () { fn4(); }, 600);

This allows each animation function to run in order, at its specified time. Presumably, the time interval between the keys of fn1 and fn2/fn3 is the length of time it takes for fn1 to complete.

API

Constructor

var choreographer = new Choreographer([duration]);

Creates a Choreographer. Optionally takes a positive integer argument to set as the default function duration.

Properties

• duration — The default length (in milliseconds) of a single animation. If Choreographer.add() is called without a duration argument, it will default to this value. If this value is not passed to the constructor, it will be set to 300.

Add

Choreographer.add(fn, [duration]);

Adds a function at the current time, which is stored as a property of the Choreographer. Increases the current time by the value passed for duration. If nothing is passed, the current time will be increased by the default set when the Choreographer was instantiated. Pass a duration of 0 to refrain from increasing the time.

Arguments

• fn — An animation function to add to the choreography.
• duration — An optional duration corresponding to the length of time it takes for fn to complete, in milliseconds.

Pause

Choreographer.pause([duration]);

Creates a pause in the choreography by increasing the current time without adding any functions.

Arguments

• duration — How long to pause (in milliseconds). Optional, and defaults to the value passed in the constructor.

Perform

Choreographer.perform();

Executes the functions stored in the choreography

License

GPLv2