    linkView.addVertex(x, y)

Add a new default vertex to the link at the coordinates provided, and let the linkView automatically determine the index of the new vertex in the vertices array. If you need to add the vertex at a custom index, use the `link.addVertex()` function instead.

This method uses the `linkView.getVertexIndex()` function to determine the index of the new vertex in the `vertices` array. The linkView checks the distance of vertices in the `link.vertices` array from the beginning of path and compares it to the distance of the added vertex. The new vertex is inserted before the first farther vertex in the `vertices` array.

This function is useful within custom `linkView` event listener definitions. The following example adds a new vertex on a double click event, instead of a pointerdown event (which is the default behavior):

    var CustomLinkView = joint.dia.LinkView.extend({
        pointerdblclick: function(evt, x, y) {
            this.addVertex(x, y);
        }
    });

    var paper = new joint.dia.Paper({
        // ...
        linkView: CustomLinkView,
        interactive: { vertexAdd: false } // disable default vertexAdd interaction
    });