Function xy

docs/app/js/sanddance-app.js:139120–139127

(d)

 * value of lineAnchor. Otherwise, use bounds of base mark.
 */ function markBoundary(marktype, grouptype, lineAnchor, markIndex) {
    const xy = (d)=>[
            d.x,
            d.x,
            d.x,
            d.y,
            d.y,
            d.y
        ];
    if (!marktype) return xy; // no reactive geometry
    else if (marktype === "line" || marktype === "area") return (d)=>xy(d.datum);
    else if (grouptype === "line") return (d)=>{