why do i see the lines joining my circles in my code?

var can = document.getElementById('canvas');
var cn = can.getContext('2d');
cn.fillStyle = 'black';
cn.fillRect(0, 0, can.width, can.height);
class object {
    constructor(r,sa,ea) {
        this.x = Math.floor(Math.random()*800);
        this.y = Math.floor(Math.random()*600);
        this.r = r;
        this.sa = sa;
        this.ea = ea;
        console.log('object successfully created')
    }
    drawcircle(){
        cn.strokeStyle = "white"
        cn.arc(this.x,this.y,this.r,this.sa,this.ea,false);
        cn.lineWidth = 3;
        cn.stroke();
    }
}
var i;
for(i = 0 ; i < 100 ; i++) {
    var circle = new object(5, 0, Math.PI*2);
    circle.drawcircle(); 
}