<script> function test() { debugger; } var object = { test: 1 }; for (var property in object) test(); </script> <p>To test, open the DevTools (Ctrl+Shift+I) and reload the page. When the debugger breaks, select the (anonymous function) node in the call stack, you should see the execution line on the call to test(). <br><br> Also set a breakpoint on the call to test(), and reload. It should break before the test() function is called.