figured out how to reuse sketches with data-attribute parameters

docs/chapters/boundingbox/bbox.js

@@ -0,0 +1,42 @@
+let curve;
+
+setup() {
+    let type = getParameter(`type`, `quadratic`);
+    if (type === `quadratic`) {
+        curve = Bezier.defaultQuadratic(this);
+    } else {
+        curve = Bezier.defaultCubic(this);
+        curve.points[2].x = 210;
+    }
+    setMovable(curve.points);
+}
+
+draw() {
+    clear();
+
+    curve.drawSkeleton();
+    curve.drawCurve();
+    curve.drawPoints();
+
+
+    let minx = Number.MAX_SAFE_INTEGER,
+        miny = minx,
+        maxx = Number.MIN_SAFE_INTEGER,
+        maxy = maxx,
+        extrema = curve.extrema();
+
+    noFill();
+    setStroke(`red`);
+
+    [0, ...extrema.x, ...extrema.y, 1].forEach(t => {
+        let p = curve.get(t);
+        if (p.x < minx) minx = p.x;
+        if (p.x > maxx) maxx = p.x;
+        if (p.y < miny) miny = p.y;
+        if (p.y > maxy) maxy = p.y;
+        if (t > 0 && t< 1) circle(p.x, p.y, 3);
+    });
+
+    setStroke(`#0F0`);
+    rect(minx, miny, maxx - minx, maxy - miny);
+}