How do I parse console.log(JSON.stringify(response)); and create a variable?

You need get JSON objects as a variable as described in this MyKong post. In your case, you likely want some line like:

var coins = response.coins;

If you're dealing with JSON string:

var obj = JSON.parse(json_string);

Once you have the object, use the dot operator to access properties:

var prop = obj.prop;

OR the array index syntax:

var prop = obj["prop"];

The meaning of that javascript line:

console.log(JSON.stringify(response));

response is some javascript object, containing properties.
JSON.stringify() converts that object into a JSON string.
console.log() writes that string string to the console window of the browser.

So you don't want to read and parse the formatted JSON string that you see in the console, because you already have that information accessible in that response object.

The structure isn't quite clear (the JSON is missing some parts), but try

console.log(response.displayName);

instead of, or next to, your original console.log line. You should see "testuser" in the console. Now you need to find an HTML element to write that value to, instead of the console.

Three for three. Every question I've posted, I've solved! So the syntax was wrong of the parse js.' var obj = (JSON.parse(JSON.stringify(response)));' That allowed me to use obj.coin. It currently returns a value of "undefined." But I have a feeling that is going to be a formatting issue of the string. So that will be a whole different question.

`    function accountDetailsResponse(response) {
        console.log (JSON.stringify(response));//logs the string to console
        console.log(response.displayName);
        document.getElementById("Coins").innerHTML = 
        (response.currencies.Coins);`

Hans, thanks again. Your code got what I needed, was precise, and you astutely cut through my awkward beginner question phrasing.

So this code was weird. The account details are is an extensive string with latitude, longitude, and every conceivable character trait on my server. The targeted variable "Coins" actually existed in two catagories. "currencies" and "reservedcurrencies." Both had different values. For some reason, the code was isolating the one that had an undefined value. So I had to get specific with (response.currencies.Coins) to specify which one I wanted. It immediately popped up with the value I was looking for on my html element. I see now that NO ONE could have helped me because I didn't include the entirety of my string. So the "undefined" result would have been impossible to diagnose.

Big lesson I learned here...don't go to the pros without details. And strings can have..."sub"strings. Or something.