Stopping a value from being updated after being defined

Question

I'm trying to have it so that upon the start of a function an "oldvalue" is created that is based on the contents of a text field, since I want certain textfields to be updated automatically until edited. So the thought behind it is that I compare the oldvalue to the value currently in the textbox that is editable and if they don't match, to stop editing that field. However when I define the oldvalue based on a non-editable textbox it keeps updating when that box is changed automatically. In other words, how do I stop a value from updating after first setting it?

function DescChanged() {
            desc = document.getElementById("Txb_Description");
            input = document.getElementById("Txb_WebArtName");
            kortinput = document.getElementById("KortBesc");
            langinput = document.getElementById("LangBesc");
            merk = document.getElementById("Brand");
            bestelnr = document.getElementById("Txb_ArticleOrderNr");
            const inputold = input;

With this if clause:

if (kortinput.value == inputold.value || isEmptyOrSpaces(kortinput.value))

Answer 1

Try having a variable outside the function, and use a temporary variable within the function, as:

var inputold = "";
function DescChanged() {
        desc = document.getElementById("Txb_Description");
        input = document.getElementById("Txb_WebArtName");
        kortinput = document.getElementById("KortBesc");
        langinput = document.getElementById("LangBesc");
        merk = document.getElementById("Brand");
        bestelnr = document.getElementById("Txb_ArticleOrderNr");
        // check if values are equal
        if (kortinput.value == inputold.value || isEmptyOrSpaces(kortinput.value))
            const inputold = input; // update the oldvalue
}