callback: set the correct this on Func object about zig-js-runtime HOT 2 CLOSED

diff --git a/src/xhr/xhr.zig b/src/xhr/xhr.zig
index 90150e4..cc4c42b 100644
--- a/src/xhr/xhr.zig
+++ b/src/xhr/xhr.zig
@@ -827,4 +827,16 @@ pub fn testExecFn(
         .{ .src = "req4.responseText.length > 64", .ex = "true" },
     };
     try checkCases(js_env, &post);
+
+    var cbk = [_]Case{
+        .{ .src = "const req5 = new XMLHttpRequest()", .ex = "undefined" },
+        .{ .src = "req5.open('GET', 'http://httpbin.io/json')", .ex = "undefined" },
+        .{ .src = "var status = 0; req5.onload = () { status = this.status };", .ex = "undefined" },
+        .{ .src = "req5.send()", .ex = "undefined" },
+
+        // Each case executed waits for all loop callaback calls.
+        // So the url has been retrieved.
+        .{ .src = "status", .ex = "200" },
+    };
+    try checkCases(js_env, &cbk);
 }