class App_20200916205824 {
	constructor( canvasId ) {
		this.cc = document.getElementById( canvasId ).getContext( "2d" );
		this.flg = true;
	}
	start() {
		this.timerId = setInterval( function() {
			this.draw( this.cc );
			this.flg = ! this.flg;
		}.bind( this ), 500 );
	}
	stop() {
		clearInterval( this.timerId );
	}
	draw( cc ) {
		cc.fillStyle = this.flg ? "orange" : "green";
		cc.fillRect( 30, 30, 130, 130 );
	}
}