Código

<canvas width="600" height="400"> </canvas>

<style>
    canvas {
        border: 1px solid lightgrey;
    }
</style>
<script>
    const 
        canvasEl = document.querySelector( 'canvas' ),
        ctx = canvasEl.getContext( '2d' );

    ctx.fillStyle = 'lightgrey';
    ctx.fillRect( 0, 0, 600, 400 ); 

    ( () => {
        const
            radio = 20,
            width = 600,
            height = 400,
            time = 5;

        let 
            x = 0,
            y = 0;

        const drawCircle = ( x, y ,radio ) => {
            ctx.fillStyle = 'blue';
            ctx.beginPath();
            ctx.arc( x, y, radio, 0, 2 * Math.PI );
            ctx.fill();
        }

        const initialState = ( inicial_x, inicial_y ) => {
            if( inicial_x == 0 )        x = inicial_x + radio;
            if( inicial_y == 0 )        y = inicial_y + radio;
            if( inicial_x == width )    x = inicial_x - radio;
            if( inicial_y == height )   y = inicial_y - radio;

            drawCircle( x, y, radio, 10 );
        }

        const clearScreen = () => {
            ctx.clearRect( 0, 0, width, height );
        }

        const move = () => {
            clearScreen();
            drawCircle( x, y, radio );
        }

        const toLeft = () => {
            const id = setInterval( () => { 
                if( x < ( 0 + radio ) ) {
                    clearInterval( id );
                    toRight();

                    return;
                }

                move();
                x--;
            }, time );
        }

        const toRight = () => {        
            const id = setInterval( () => { 
                if( x > ( width - radio ) ) {
                    clearInterval( id );
                    toLeft();

                    return;
                }

                move();
                x++;
            }, time );
        }

        const start = () => setTimeout( () => {   
            toLeft();
        }, 3000 );

        initialState( 0, 0 );
        start();
    })();


</script> 

Resultado en mi CodePen

https://codepen.io/pen?template=poLavgm