Javascript get text input value
var inputValue = document.getElementById("myTextInputID").value;
javascript get element by id
var element = document.getElementById("YourElementId");
get value from textbox in vanilla javascript
document.getElementById("myText").value = "Johnny Bravo";
value from getelementbyid
document.getElementById('numbers').value
Finding HTML Element by Id
var myElement = document.getElementById("intro");
get document by id
var element = document.getElementById(id);