绘制一段虚线

<svg width="500" height="500">
    <path stroke="purple" fill="none" d="M0 250 H500" stroke-dasharray="20 10 5 5"></path>
</svg>

将虚线移出

<svg width="500" height="500">
    <path stroke="purple" fill="none" d="M0 250 H500" stroke-dasharray="500" stroke-dashoffset="500"></path>
</svg>

鼠标移到SVG上开始画线