how to change input value in javascript code example

Example 1: javascript set input field value

document.getElementById("myInputID").value = "My Value"; //set value on myInputID

Example 2: Javascript get text input value

var inputValue = document.getElementById("myTextInputID").value;

Example 3: javascript input value change

function updateInput(ish){
    document.getElementById("fieldname").value = ish;
}