Uncaught ReferenceError: test is not defined at HTMLInputElement.onclick

Question

i want to call a function using button

here is my sample code

<input type="button" value="click" onclick="test()">

function test() {
    alert("test");
}

here is my error

(index):39 Uncaught ReferenceError: test is not defined
    at HTMLInputElement.onclick ((index):39)
onclick @ (index):39

sample preview https://jsfiddle.net/d102791estiny/1b68eLdr/16745/