3 files changed, 40 insertions, 11 deletions
diff --git a/runtime/shared.rs b/runtime/shared.rs
index 1b2136c63..c52521690 100644
--- a/runtime/shared.rs
+++ b/runtime/shared.rs
@@ -116,3 +116,26 @@ pub fn maybe_transpile_source(
 
   Ok((source_text.into(), maybe_source_map))
 }
+
+pub fn import_assertion_callback(
+  args: deno_core::ImportAssertionsSupportCustomCallbackArgs,
+) {
+  let mut msg = deno_terminal::colors::yellow("⚠️  Import assertions are deprecated. Use `with` keyword, instead of 'assert' keyword.").to_string();
+  if let Some(specifier) = args.maybe_specifier {
+    if let Some(source_line) = args.maybe_source_line {
+      msg.push_str("\n\n");
+      msg.push_str(&source_line);
+      msg.push_str("\n\n");
+    }
+    msg.push_str(&format!(
+      "  at {}:{}:{}\n",
+      specifier,
+      args.maybe_line_number.unwrap(),
+      args.column_number
+    ));
+    #[allow(clippy::print_stderr)]
+    {
+      eprintln!("{}", msg);
+    }
+  }
+}
diff --git a/runtime/web_worker.rs b/runtime/web_worker.rs
index ed1e19c9e..3e95045db 100644
--- a/runtime/web_worker.rs
+++ b/runtime/web_worker.rs
@@ -538,6 +538,13 @@ impl WebWorker {
       options.bootstrap.enable_op_summary_metrics,
       options.strace_ops,
     );
+    let import_assertions_support = if options.bootstrap.future {
+      deno_core::ImportAssertionsSupport::Error
+    } else {
+      deno_core::ImportAssertionsSupport::CustomCallback(Box::new(
+        crate::shared::import_assertion_callback,
+      ))
+    };
 
     let mut js_runtime = JsRuntime::new(RuntimeOptions {
       module_loader: Some(options.module_loader.clone()),
@@ -558,6 +565,7 @@ impl WebWorker {
       validate_import_attributes_cb: Some(Box::new(
         validate_import_attributes_callback,
       )),
+      import_assertions_support,
       ..Default::default()
     });
 
diff --git a/runtime/worker.rs b/runtime/worker.rs
index 696786b56..c1c918d08 100644
--- a/runtime/worker.rs
+++ b/runtime/worker.rs
@@ -476,6 +476,14 @@ impl MainWorker {
       }
     });
 
+    let import_assertions_support = if options.bootstrap.future {
+      deno_core::ImportAssertionsSupport::Error
+    } else {
+      deno_core::ImportAssertionsSupport::CustomCallback(Box::new(
+        crate::shared::import_assertion_callback,
+      ))
+    };
+
     let mut js_runtime = JsRuntime::new(RuntimeOptions {
       module_loader: Some(options.module_loader.clone()),
       startup_snapshot: options.startup_snapshot,
@@ -501,6 +509,7 @@ impl MainWorker {
       validate_import_attributes_cb: Some(Box::new(
         validate_import_attributes_callback,
       )),
+      import_assertions_support,
       eval_context_code_cache_cbs: options.v8_code_cache.map(|cache| {
         let cache_clone = cache.clone();
         (
@@ -544,17 +553,6 @@ impl MainWorker {
     if let Some(op_summary_metrics) = op_summary_metrics {
       js_runtime.op_state().borrow_mut().put(op_summary_metrics);
     }
-    extern "C" fn message_handler(
-      _msg: v8::Local<v8::Message>,
-      _exception: v8::Local<v8::Value>,
-    ) {
-      // TODO(@littledivy): Propogate message to users.
-    }
-
-    // Register message listener
-    js_runtime
-      .v8_isolate()
-      .add_message_listener(message_handler);
 
     if let Some(server) = options.maybe_inspector_server.clone() {
       server.register_inspector(