3 files changed, 29 insertions, 3 deletions
diff --git a/runtime/js/30_os.js b/runtime/js/30_os.js
index 15df6f554..f6bada6a5 100644
--- a/runtime/js/30_os.js
+++ b/runtime/js/30_os.js
@@ -31,7 +31,14 @@
     exitHandler = fn;
   }
 
-  function exit(code = 0) {
+  function exit(code) {
+    // Set exit code first so unload event listeners can override it.
+    if (typeof code === "number") {
+      core.opSync("op_set_exit_code", code);
+    } else {
+      code = 0;
+    }
+
     // Dispatches `unload` only when it's not dispatched yet.
     if (!window[SymbolFor("isUnloadDispatched")]) {
       // Invokes the `unload` hooks before exiting
@@ -44,7 +51,7 @@
       return;
     }
 
-    core.opSync("op_exit", code);
+    core.opSync("op_exit");
     throw new Error("Code not reachable");
   }
 
diff --git a/runtime/lib.rs b/runtime/lib.rs
index fb6159dd9..ca250ce20 100644
--- a/runtime/lib.rs
+++ b/runtime/lib.rs
@@ -1,5 +1,7 @@
 // Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
 
+use std::sync::atomic::AtomicI32;
+
 pub use deno_broadcast_channel;
 pub use deno_console;
 pub use deno_crypto;
@@ -29,3 +31,12 @@ pub mod worker;
 
 mod worker_bootstrap;
 pub use worker_bootstrap::BootstrapOptions;
+
+// The global may not be very elegant but:
+//
+// 1. op_exit() calls std::process::exit() so there is not much point storing
+//    the exit code in runtime state
+//
+// 2. storing it in runtime state makes retrieving it again in cli/main.rs
+//    unduly complicated
+pub static EXIT_CODE: AtomicI32 = AtomicI32::new(0);
diff --git a/runtime/ops/os.rs b/runtime/ops/os.rs
index 0a6269ac5..8e96de75d 100644
--- a/runtime/ops/os.rs
+++ b/runtime/ops/os.rs
@@ -10,6 +10,7 @@ use deno_core::OpState;
 use serde::Serialize;
 use std::collections::HashMap;
 use std::env;
+use std::sync::atomic::Ordering::Relaxed;
 
 pub fn init() -> Extension {
   Extension::builder()
@@ -23,6 +24,7 @@ pub fn init() -> Extension {
       ("op_hostname", op_sync(op_hostname)),
       ("op_loadavg", op_sync(op_loadavg)),
       ("op_os_release", op_sync(op_os_release)),
+      ("op_set_exit_code", op_sync(op_set_exit_code)),
       ("op_system_memory_info", op_sync(op_system_memory_info)),
     ])
     .build()
@@ -95,7 +97,13 @@ fn op_delete_env(
   Ok(())
 }
 
-fn op_exit(_state: &mut OpState, code: i32, _: ()) -> Result<(), AnyError> {
+fn op_set_exit_code(_: &mut OpState, code: i32, _: ()) -> Result<(), AnyError> {
+  crate::EXIT_CODE.store(code, Relaxed);
+  Ok(())
+}
+
+fn op_exit(_: &mut OpState, _: (), _: ()) -> Result<(), AnyError> {
+  let code = crate::EXIT_CODE.load(Relaxed);
   std::process::exit(code)
 }