setAttribute is not working in JavaScript

Question

I am using setAttribue as below. Its working only for first time and after that the changing value is showing the alert but not setting with document.getElementById("to").setAttribute("value", selValue);

document.getElementById("listcontact").onchange = function () {
    var selIndex = document.getElementById("listcontact").selectedIndex;
    var selValue = document.getElementById("listcontact").options[selIndex].innerHTML;
    var contactVal = selValue.split(';');      
    var phone = contactVal[2];  

    alert(phone);
    document.getElementById("to").setAttribute("value", selValue);
    selIndex = "";
    selValue = "";
    phone = "";
    selValue = "";
};

Why is this not working as I expect and how can I fix it?

Answer 1

The value attribute sets the initial value, not the current value.

Assign something to the value property instead.

document.getElementById("to").value = selValue;

Answer 2

You can use like this:

document.getElementById("to").value = selValue;