The insertItemBefore() method of the SVGPointList interface inserts a point before another item in the list.

obj

An SVGPoint object containing the coordinates of the point to be inserted.

index

The index of the item the object should be inserted before. If the index passed in is greater than the length of the list, then index will be set to the list length and the item inserted before the last item in the list.

The SVGPoint object that was inserted.

NoModificationAllowedError DOMException

Thrown if the list is read-only.

The following example shows an SVG which contains a <polyline> with five coordinate pairs. A new SVGPoint is created, and inserted before the point at index 2.

<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");
let svgpoint = document.getElementById("svg").createSVGPoint();
svgpoint.y = 10;
svgpoint.x = 10;
console.log(example.points.insertItemBefore(svgpoint, 2));