how to get value of textbox in javascript from html

1<!--
2This is example is with a number...
3But you can do it with whatever input type you want
4-->
5<input type="number" name="numberInput" id="numberInput" max="20" min="1" step="1">
6<button type="button" onclick="myFunction()">sumbit</button>
7
8<script>
9  function myFunction() {
10    let tokenAmount = document.getElementById("numberInput").value;
11    return // whatever you want to do with it
12  }
13</script>

1let link = document.getElementById("link_box").value
2    console.log(link)
3    document.getElementById("link_box").value = "";