Single-file JavaScript module: object-based animations for CSS-managed DOM manipulation

Animaniac-v1.1.0.js

/* Object-based  for DOM animation management of style properties.
*/

define(function(require, exports, module) {
    function Animaniac() {
        /* Initializes animation object with default parameters. Users will
           typically assign the following properties before calling "start()":
            * element (the relevant DOM element)
            * properties (style property keys with 2-element initial/final values Array)
            * callback (what to invoke when the transition has finished)
        */
        this.handle = null;
        this.started = new Date();
        this.interval = 10; // ms
        this._element = null;
        this.properties = {};
        this._duration = 1000;
        this.callback = function() {};
        return this;
    };

    Animaniac.prototype.element = function(element) {
        this._element = element;
        return this;
    };

    Animaniac.prototype.duration = function(dt_s) {
        this._duration = dt_s * 1e3;
        return this;
    }

    Animaniac.prototype.prop = function(prop, vals, suffix="") {
        /*
        */
        this.properties[prop] = [vals[0], vals[1], suffix];
        return this;
    };

    Animaniac.prototype.start = function() {
        /* Kicks off setInterval() call to update animation properties.
        */
        this.started = new Date();
        this.handle = setInterval(this.onInterval.bind(this), this.interval);
    };

    Animaniac.prototype.onInterval = function() {
        /* Updates style properties via interpolation. Upon completion, final
           properties are assigned and interval handle is cleared.
        */
        let dt_ms = (new Date()) - this.started;
        let pct = dt_ms / this._duration;
        Object.keys(this.properties).forEach(function(key) {
            let values = this.properties[key];
            this._element.style[key] = (values[0] + pct * (values[1] - values[0])) + values[2];
        }, this);
        if (pct >= 1.0) {
            Object.keys(this.properties).forEach(function(key) {
                this._element.style[key] = this.properties[key][1] + this.properties[key][2];
            }, this);
            clearInterval(this.handle);
            this.callback();
        }
    };

    Object.assign(exports, {
        "Animaniac": Animaniac,
        "__uni__": "com.github.gist.tythos.animaniac",
        "__semver__": "1.1.0",
        "__author__": "code@tythos.net"
    });
});