ignore / if the delimiter is something else

(note: I don't think this is the correct fix! But at least it gives a unit test)

closes #1849

Author: Fil

src/transforms/tree.js

@@ -169,7 +169,7 @@ function nodeData(field) {
 function normalizer(delimiter = "/") {
   return `${delimiter}` === "/"
     ? (P) => P // paths are already slash-separated
-    : (P) => P.map(replaceAll(delimiter, "/")); // TODO string.replaceAll when supported
+    : (P) => P.map(replaceAll("/", "\\/")).map(replaceAll(delimiter, "/")); // TODO string.replaceAll when supported
 }
 
 function replaceAll(search, replace) {
@@ -272,7 +272,7 @@ function parentValue(evaluate) {
 function nameof(path) {
   let i = path.length;
   while (--i > 0) if (slash(path, i)) break;
-  return path.slice(i + 1);
+  return path.slice(i + 1).replaceAll("\\/", "/");
 }
 
 // Slashes can be escaped; to determine whether a slash is a path delimiter, we

test/output/treeDelimiter.svg

@@ -298,6 +298,7 @@ export * from "./title.js";
 export * from "./traffic-horizon.js";
 export * from "./travelers-covid-drop.js";
 export * from "./travelers-year-over-year.js";
+export * from "./tree-delimiter.js";
 export * from "./uniform-random-difference.js";
 export * from "./untyped-date-bin.js";
 export * from "./us-congress-age-color-explicit.js";

test/plots/index.ts

@@ -0,0 +1,21 @@
+import * as Plot from "@observablehq/plot";
+
+export async function treeDelimiter() {
+  return Plot.plot({
+    axis: null,
+    height: 100,
+    margin: 10,
+    marginLeft: 40,
+    marginRight: 190,
+    marks: [
+      Plot.tree(
+        [
+          "foo;bar;http://www.example.com",
+          "foo;bar;https://www.example.com/posts/1",
+          "foo;baz;https://www.example.com/posts/2"
+        ],
+        {delimiter: ";"}
+      )
+    ]
+  });
+}