I do not understand why I get this error?

Question

Why do I always get an error on myfunc() is not defined?

<button onclick = "myfunc();">submit</button>
<script src="script.js">
   function myfunc(){
     let person = {
       name: document.getElementById("demo");
     }
     alert(person.name);
   }
</script>

Answer 1

Its a basic fact, your script gets ignored if that script tag has an src attribute

Solution: make a second script tag with no src attribute.

<button onclick="myfunc();">submit</button>
<script src="script.js"></script>
<script>
   function myfunc(){
     let person = {
       name: document.getElementById("demo")
     }
     alert("it works");
   }
</script>