The replaceItem() method of the SVGPointList interface replaces a point in the list.

obj

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

index

The index of the item to replace.

The new SVGPoint object.

NoModificationAllowedError DOMException

Thrown if the list is read-only.

IndexSizeError DOMException

Thrown if the index passed in is greater than the number of items in the list.

The following example shows an SVG which contains a <polyline> with five coordinate pairs. A new SVGPoint is created, then replaces the point at index 1 (the second item in the list).

<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.replaceItem(svgpoint, 1));