The numberOfItems read-only property of the SVGPointList interface returns the number of items in the list.
The number of items in the list.
The following example shows an SVG which contains a <polyline> with five coordinate pairs. The numberOfItems property returns 5.
<svg id="svg" viewBox="-10 -10 120 120" xmlns="http://www.w3.org/2000/svg">
<polyline
id="example"
stroke="black"
fill="none"
points="50,0 21,90 98,35 2,35 79,90" />
</svg>let example = document.getElementById("example");
console.log(example.points.numberOfItems); // 5