More tweaks to propagator prototype.

1 files changed, 27 insertions, 20 deletions

diff --git a/chapter-7/propagators.js b/chapter-7/propagators.js
index c392ad1..fe0034a 100644
--- a/chapter-7/propagators.js
+++ b/chapter-7/propagators.js
@@ -1,23 +1,30 @@
 window.addEventListener("load", async () => {
-  await Scheme.load_main("propagators.wasm", {
-    reflect_wasm_dir: "hoot",
-    user_imports: {
-      window: {
-        setTimeout: setTimeout
-      },
-      document: {
-        makeTextNode: Document.prototype.createTextNode.bind(document),
-        makeElement: Document.prototype.createElement.bind(document),
-        body: () => document.body,
-      },
-      element: {
-        appendChild: (parent, child) => parent.appendChild(child),
-        setAttribute: (elem, attr, value) => elem.setAttribute(attr, value),
-        getValue: (elem) => elem.value,
-        setValue: (elem, val) => elem.value = val,
-        replaceWith: (oldElem, newElem) => oldElem.replaceWith(newElem),
-        addEventListener: (elem, name, f) => elem.addEventListener(name, f)
-      },
+  try {
+    await Scheme.load_main("propagators.wasm", {
+      reflect_wasm_dir: "hoot",
+      user_imports: {
+        window: {
+          setTimeout: setTimeout
+        },
+        document: {
+          makeTextNode: Document.prototype.createTextNode.bind(document),
+          makeElement: Document.prototype.createElement.bind(document),
+          body: () => document.body,
+        },
+        element: {
+          appendChild: (parent, child) => parent.appendChild(child),
+          setAttribute: (elem, attr, value) => elem.setAttribute(attr, value),
+          getValue: (elem) => elem.value,
+          setValue: (elem, val) => elem.value = val,
+          replaceWith: (oldElem, newElem) => oldElem.replaceWith(newElem),
+          addEventListener: (elem, name, f) => elem.addEventListener(name, f)
+        },
+      }
+    });
+  } catch(e) {
+    if(e instanceof WebAssembly.CompileError) {
+      document.getElementById("wasm-error").hidden = false;
     }
-  });
+    throw e;
+  }
 });