Global variable declaration returns undefined, any reason for this

When I log input to the console, it returns undefined but when put inside a the anonymous function, it logs to the console as expected

I had tried the below code, and expected that the inputValue to be logged to the console on click of the addButton, however, the value from inputValue when logged was undefined, the value of inputValue is meant to be gotten from an inputbox.

`

const addButton=document.querySelector(".addButton");
let listBox=document.querySelector(".listBox");
let input=document.querySelector(".addtext").value;
let inputValue=input;
addButton.addEventListener('click',()=>{
console.log(inputValue)});

</script>
</body>
</html>`