Fixes in various places in existing code

Cargo.toml

@@ -28,6 +28,7 @@ form_urlencoded = "1.2"
 futures-channel = "0.3"
 futures-lite = "2"
 futures-util = "0.3"
+heck = "0.5"
 http = "1"
 http-body = "1"
 http-body-util = "0.1"

README.md

@@ -59,6 +59,14 @@ console.log(greet("world"));
 starlingmonkey main.js
 ```
 
+JSON modules are imported with an import attribute, and `import()` loads a module
+dynamically:
+
+```js
+import config from "./config.json" with { type: "json" };
+const { greet } = await import("./greet.js");
+```
+
 For quick one-liners, use `-e`:
 
 ```bash
@@ -141,9 +149,17 @@ is `undefined` at the top level.
 **Legacy script mode** (`--legacy-script`) — sloppy mode, no
 `import`/`export`, `this` is the global object.
 
-**Exit status** — `0` when the script and all the work it scheduled complete, `1`
-when the script throws or an initializer, the event loop or the runtime fails (the
-error is printed to stderr), and `2` for invalid command-line arguments.
+**Output** — `console.log`, `console.info` and `console.debug` print to stdout,
+and `console.warn` and `console.error` print to stderr with a `Warn:` or `Error:`
+prefix. An exception a timer or other task throws is reported on stderr as
+`Uncaught` with its message and stack, and a promise rejected with no handler as
+`Uncaught (in promise)` with the reason's.
+
+**Exit status** — `0` when the script and all the work it scheduled complete,
+including when a promise rejected with no handler. `1` when the script throws,
+its top-level `await` rejects or never settles, or an initializer, the event loop
+or the runtime fails, with the error printed to stderr. `2` for invalid
+command-line arguments.
 
 ---
 
@@ -608,7 +624,7 @@ impl Fetcher {
 ```
 
 The method returns the `Promise` to JS immediately, and the future is queued on
-the event loop. `core_runtime::event_loop::run_to_completion`, which
+the event loop. `ScriptEvaluation::run_to_completion`, which
 `libstarling::run` drives for you, polls it and settles the `Promise` with the
 future's `Ok`/`Err`. Two other constructors cover the cases `new` doesn't:
 `PromiseFuture::new_void` for futures resolving to `()`, and `PromiseFuture::from_value`

crates/builtins/cpp-builtins/cpp/builtins/console.cpp

@@ -405,33 +405,24 @@ JS::Result<mozilla::Ok> ToSource(JSContext *cx, std::string &sourceOut, JS::Hand
 
 namespace builtins::web::console {
 
+// `log`, `info` and `debug` print the bare message on stdout. `warn` and `error` print it on
+// stderr, prefixed with the level.
 __attribute__((weak))
 void builtin_impl_console_log(Console::LogType log_ty, const char *msg) {
-  const char *prefix = nullptr;
   switch (log_ty) {
-  case Console::LogType::Log:
-    prefix = "Log";
-    break;
-  case Console::LogType::Debug:
-    prefix = "Debug";
-    break;
-  case Console::LogType::Info:
-    prefix = "Info";
-    break;
   case Console::LogType::Warn:
-    prefix = "Warn";
-    break;
+    fprintf(stderr, "Warn: %s\n", msg);
+    fflush(stderr);
+    return;
   case Console::LogType::Error:
-    prefix = "Error";
-    break;
+    fprintf(stderr, "Error: %s\n", msg);
+    fflush(stderr);
+    return;
   default:
-    prefix = "";
-    break;
+    fprintf(stdout, "%s\n", msg);
+    fflush(stdout);
+    return;
   }
-  MOZ_ASSERT(prefix);
-
-  fprintf(stdout, "%s: %s\n", prefix, msg);
-  fflush(stdout);
 }
 
 template <Console::LogType log_ty>
@@ -470,9 +461,9 @@ static bool console_out(JSContext *cx, unsigned argc, JS::Value *vp) {
 static bool assert_(JSContext *cx, unsigned argc, JS::Value *vp) {
   JS::CallArgs args = CallArgsFromVp(argc, vp);
   args.rval().setUndefined();
-  auto condition = args.get(0).toBoolean();
+  bool condition = JS::ToBoolean(args.get(0));
   // 1. If condition is true, return.
-  if (!condition) {
+  if (condition) {
     return true;
   }
 
@@ -486,27 +477,27 @@ static bool assert_(JSContext *cx, unsigned argc, JS::Value *vp) {
   // 4.3. Otherwise:
   // 4.3.1. Let concat be the concatenation of message, U+003A (:), U+0020
   // SPACE, and first. 4.3.2. Set data[0] to concat.
+  // The data are the arguments after the condition. A string first datum is
+  // joined to the message with ": ", and any other one follows it after a space.
   auto length = args.length();
   if (length > 1) {
-    message += ": ";
+    if (args.get(1).isString()) {
+      message += ":";
+    }
     JS::RootedObjectVector visitedObjects(cx);
-    for (int i = 0; i < length; i++) {
+    for (unsigned i = 1; i < length; i++) {
       JS::HandleValue arg = args.get(i);
       std::string source;
       auto result = ToSource(cx, source, arg, &visitedObjects);
       if (result.isErr()) {
         return false;
       }
       // strip quotes for direct string logs
-      if (source[0] == '"' && source[source.length() - 1] == '"') {
+      if (source.length() >= 2 && source[0] == '"' && source[source.length() - 1] == '"') {
         source = source.substr(1, source.length() - 2);
       }
-      if (!message.empty()) {
-        message += " ";
-        message += source;
-      } else {
-        message += source;
-      }
+      message += " ";
+      message += source;
     }
   }
 

crates/builtins/web-streams/Cargo.toml

@@ -11,7 +11,7 @@ edition.workspace = true
 test = false
 
 [dependencies]
-smallvec = "1.16"
+smallvec.workspace = true
 core-runtime.workspace = true
 js.workspace = true
 web-globals.workspace = true

crates/core-runtime/src/config.rs

@@ -132,7 +132,9 @@ pub struct RuntimeConfig {
     #[command(flatten)]
     pub serve_limits: ServeLimits,
 
-    /// Pre-initialize the runtime (used during wizer snapshot).
+    /// Pre-initialize the runtime for a Wizer snapshot. The runtime then records where each piece
+    /// of asynchronous work is created, for reporting work still pending when the snapshot is
+    /// taken (see [`EventLoop::ensure_idle_for_snapshot`](crate::event_loop::EventLoop::ensure_idle_for_snapshot)).
     #[arg(skip)]
     pub pre_initialize: bool,
 }