How can I dynamically update the JSON-LD script with Ajax?

I have JSON-LD as shown, where ratingValue and ratingCount are coming from backend, but I want do it from UI through Ajax call and update it in the aggregateRating.

But when opened page source it is showing data coming from the backend, but when I do console.log() it is showing the value expected but it is not updated in page source.

Is there any way possibly do it from the UI side?

<script type="application/ld+json"> {
    "@context": "http://schema.org/",
    "@type": "Product",
    "name": "Phone",

    "aggregateRating": {
        "@type": "AggregateRating",
        "ratingValue": "4.5",
        "ratingCount": "80"
    },
    "offers": {
        "@type": "AggregateOffer",
        "lowPrice": "5",
        "highPrice": "10",
        "priceCurrency": "USD",
        "availability": "http://schema.org/InStock"
    }
}
</script>

(function () {
    var id = $ {
        prdId
    };
    var response = "";
    $.ajax({
        url: url;
        dataType: "jsonp",
        data: {
            pid: id,
            _method: "GET",
            t: new Date().getTime()
        },
        timeout: 20000,
        xhrFields: {
            withCredentials: true
        },
        type: "get",
        success: function (json) {
            if (json.success == true) {
                response = json.data;
                //call api
                structureData(response);
            } else {
                response = "error";
            }

        }
    });


    function structureData(resp) {
        var json = document.querySelector('script[type="application/ld+json"]').textContent;
        json = JSON.parse(json);

        json["aggregateRating"] = {
            "@type": "AggregateRating",
            "ratingValue": resp.averageScore,
            "reviewCount": resp.averageScore
        }
        var jso = JSON.stringify(json);

        document.querySelector('script[type="application/ld+json"]').textContent = jso;

    }
}

Solution

You can definitely update JSON-LD dynamically, this is a more crude example - but you can run the code snippet and see it working. I found the code through this SO question about roughly the same topic but modified it to match your example better:

let jsonLdScript = document.querySelector('script[type="application/ld+json"]');
let jsonld = JSON.parse(jsonLdScript.innerText);

document.getElementById('orig-result').textContent = jsonLdScript.innerText;

jsonld.aggregateRating.ratingValue = "5";
jsonld.aggregateRating.ratingCount = "95";

let newJson = JSON.stringify(jsonld);

jsonLdScript.innerHTML = newJson;

document.getElementById('result').textContent = jsonLdScript.innerText;

<html>
  <head>
  <script type="application/ld+json"> 
  {
    "@context": "http://schema.org/",
    "@type": "Product",
    "name": "Phone",
    "aggregateRating": {
        "@type": "AggregateRating",
        "ratingValue": "4.5",
        "ratingCount": "80"
    },
    "offers": {
        "@type": "AggregateOffer",
        "lowPrice": "5",
        "highPrice": "10",
        "priceCurrency": "USD",
        "availability": "http://schema.org/InStock"
    }
  }
  </script>
  </head>
  <body>
    <p>Original Output JSON-LD: <br /><strong id="orig-result"></strong></p>
    <p>New Output JSON-LD: <br /><strong id="result"></strong></p>
  </body>
</html>

How are you testing? A few things to keep in mind:

Obviously the raw page DOM won't be modified
You should see the changes in dev tools
If you're using Googles Structured Data Tool, and the original JSON is parsed before your function updates it, I'd wager Google won't catch the change.
If you're using querySelector, might want to confirm that the JSON-LD you intend to modify is the first instance of JSON-LD on the page.