From 5ba4c7f1b655732ef783e37b37d99d8afedc232a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sa=C3=BAl=20Ibarra=20Corretg=C3=A9?= <s@saghul.net>
Date: Tue, 21 Nov 2023 15:51:16 +0100
Subject: [PATCH] Add queueMicrotask

Ref: https://github.com/quickjs-ng/quickjs/issues/16
---
 Makefile                      |  1 +
 quickjs.c                     | 17 +++++++
 tests/test_queue_microtask.js | 84 +++++++++++++++++++++++++++++++++++
 3 files changed, 102 insertions(+)
 create mode 100644 tests/test_queue_microtask.js

diff --git a/Makefile b/Makefile
index ae37d2b8..a837445d 100644
--- a/Makefile
+++ b/Makefile
@@ -64,6 +64,7 @@ test: build
 	$(QJS) tests/test_loop.js
 	$(QJS) tests/test_std.js
 	$(QJS) tests/test_worker.js
+	$(QJS) tests/test_queue_microtask.js
 
 test262: build
 	$(RUN262) -m -c test262.conf -a
diff --git a/quickjs.c b/quickjs.c
index 9e8d7f9a..b2f8f028 100644
--- a/quickjs.c
+++ b/quickjs.c
@@ -33745,6 +33745,22 @@ static JSValue js_global_isFinite(JSContext *ctx, JSValueConst this_val,
     return JS_NewBool(ctx, res);
 }
 
+static JSValue js_microtask_job(JSContext *ctx,
+                                int argc, JSValueConst *argv)
+{
+    return JS_Call(ctx, argv[0], ctx->global_obj, 0, NULL);
+}
+
+static JSValue js_global_queueMicrotask(JSContext *ctx, JSValueConst this_val,
+                                        int argc, JSValueConst *argv)
+{
+    if (check_function(ctx, argv[0]))
+        return JS_EXCEPTION;
+    if (JS_EnqueueJob(ctx, js_microtask_job, 1, &argv[0]))
+        return JS_EXCEPTION;
+    return JS_UNDEFINED;
+}
+
 /* Object class */
 
 static JSValue JS_ToObject(JSContext *ctx, JSValueConst val)
@@ -45683,6 +45699,7 @@ static const JSCFunctionListEntry js_global_funcs[] = {
     JS_CFUNC_DEF("parseFloat", 1, js_parseFloat ),
     JS_CFUNC_DEF("isNaN", 1, js_global_isNaN ),
     JS_CFUNC_DEF("isFinite", 1, js_global_isFinite ),
+    JS_CFUNC_DEF("queueMicrotask", 1, js_global_queueMicrotask ),
 
     JS_CFUNC_MAGIC_DEF("decodeURI", 1, js_global_decodeURI, 0 ),
     JS_CFUNC_MAGIC_DEF("decodeURIComponent", 1, js_global_decodeURI, 1 ),
diff --git a/tests/test_queue_microtask.js b/tests/test_queue_microtask.js
new file mode 100644
index 00000000..106dde43
--- /dev/null
+++ b/tests/test_queue_microtask.js
@@ -0,0 +1,84 @@
+function assert(actual, expected, message) {
+    if (arguments.length == 1)
+        expected = true;
+
+    if (actual === expected)
+        return;
+
+    if (actual !== null && expected !== null
+    &&  typeof actual == 'object' && typeof expected == 'object'
+    &&  actual.toString() === expected.toString())
+        return;
+
+    throw Error("assertion failed: got |" + actual + "|" +
+                ", expected |" + expected + "|" +
+                (message ? " (" + message + ")" : ""));
+}
+
+function assert_throws(expected_error, func)
+{
+    var err = false;
+    try {
+        func();
+    } catch(e) {
+        err = true;
+        if (!(e instanceof expected_error)) {
+            throw Error("unexpected exception type");
+        }
+    }
+    if (!err) {
+        throw Error("expected exception");
+    }
+}
+
+function assert_array_equals(a, b) {
+    if (!Array.isArray(a) || !Array.isArray(b))
+        return assert(false);
+
+    assert(a.length === b.length);
+
+    a.forEach((value, idx) => {
+        assert(b[idx] === value);
+    });
+}
+
+// load more elaborate version of assert if available
+try { std.loadScript("test_assert.js"); } catch(e) {}
+
+function test_types() {
+  assert_throws(TypeError, () => queueMicrotask(), "no argument");
+  assert_throws(TypeError, () => queueMicrotask(undefined), "undefined");
+  assert_throws(TypeError, () => queueMicrotask(null), "null");
+  assert_throws(TypeError, () => queueMicrotask(0), "0");
+  assert_throws(TypeError, () => queueMicrotask({ handleEvent() { } }), "an event handler object");
+  assert_throws(TypeError, () => queueMicrotask("window.x = 5;"), "a string");
+}
+
+function test_async() {
+  let called = false;
+  queueMicrotask(() => {
+    called = true;
+  });
+  assert(!called);
+}
+
+function test_arguments() {
+  queueMicrotask(function () { // note: intentionally not an arrow function
+    assert(arguments.length === 0);
+  }, "x", "y");
+};
+
+function test_async_order() {
+  const happenings = [];
+  Promise.resolve().then(() => happenings.push("a"));
+  queueMicrotask(() => happenings.push("b"));
+  Promise.reject().catch(() => happenings.push("c"));
+  queueMicrotask(() => {
+    assert_array_equals(happenings, ["a", "b", "c"]);
+  });
+}
+
+test_types();
+test_async();
+test_arguments();
+test_async_order();