如何用KonvaJS用鼠标画箭头？

<script src="konva.min.js"></script>

<div id="container"></div>

var container = document.getElementById('container');
var stage = new Konva.Stage({
    container: 'container',
    width: window.innerWidth,
    height: window.innerHeight
});

var layer = new Konva.Layer();
stage.add(layer);

var arrow = new Konva.Arrow({
    x: 0,
    y: 0,
    points: [0, 0, 100, 100], // 箭头的坐标点
    pointerLength: 20, // 箭头的长度
    pointerWidth: 20, // 箭头的宽度
    fill: 'black', // 箭头的填充颜色
    stroke: 'black', // 箭头的边框颜色
    strokeWidth: 2 // 箭头的边框宽度
});

layer.add(arrow);
stage.add(layer);

stage.on('mousemove', function (e) {
    var pos = stage.getPointerPosition();
    arrow.points([0, 0, pos.x, pos.y]);
    layer.batchDraw();
});