index.js
function(){
        this.frameCount++;
        /** @private */
        var now = Date.now();
        this.__lastTime = this.__lastTime || now;
        this.deltaTime = (this.fixedDelta || exports.globalFixedDelta) ? 1000/Math.min(60, this.__fps) : now - this.__lastTime;
        this.elapsedTime += this.deltaTime;
        this.__lastTime = now;

        this.emit('update', this.deltaTime, this.elapsedTime, this.frameCount);
        return this;
    }
function(){
        this.frameCount++;
        /** @private */
        var now = Date.now();
        this.__lastTime = this.__lastTime || now;
        this.deltaTime = (this.fixedDelta || exports.globalFixedDelta) ? 1000/Math.min(60, this.__fps) : now - this.__lastTime;
        this.elapsedTime += this.deltaTime;
        this.__lastTime = now;

        this.emit('update', this.deltaTime, this.elapsedTime, this.frameCount);
        return this;
    }
function ( ) { this . frameCount ++ ; /** @private */ var now = Date . now ( ) ; this . __lastTime = this . __lastTime || now ; this . deltaTime = ( this . fixedDelta || exports . globalFixedDelta ) ? 1000 / Math . min ( 60 , this . __fps ) : now - this . __lastTime ; this . elapsedTime += this . deltaTime ; this . __lastTime = now ; this . emit ( 'update' , this . deltaTime , this . elapsedTime , this . frameCount ) ; return this ; }
update the animation loop once

@emit Animitter#update
@return {Animitter}
update the animation loop once