The error code NS_ERROR_DOM_DATA_CLONE_ERR is a common issue encountered in web applications when attempting to clone data that cannot be serialized properly. This problem frequently arises in JavaScript when working with postMessage, localStorage, or when trying to serialize objects that contain unsupported data types such as functions, DOM elements, or File objects.

In this article, we will explain how this error occurs and how you can effectively fix it.

Causes of NS_ERROR_DOM_DATA_CLONE_ERR

The NS_ERROR_DOM_DATA_CLONE_ERR can occur in the following scenarios:

• Using unsupported data types: JavaScript does not natively support cloning certain objects, such as functions, DOM elements, cyclic structures, or instances of classes like File, Blob, or ImageData.
• Incorrect data transmission via postMessage: The error often arises when attempting to transfer data between windows or worker processes using postMessage, where the data is incompatible with the cloning process.
• Direct manipulation of objects: Attempts to store complex data structures in localStorage or sessionStorage, which must be serialized into strings, can also trigger this error.

How to Identify What Causes NS_ERROR_DOM_DATA_CLONE_ERR

First, it's essential to understand which types of data are problematic. You can take the following steps to identify the issue:

1. Check what data you are cloning: If you are using postMessage, localStorage, or another method of transferring or storing data, ensure that it does not include functions, DOM elements, or cyclic references.
2. Try serializing using JSON: Most data can be checked by attempting to convert the data to JSON format using JSON.stringify(). If an error occurs during serialization, you have likely encountered a problematic data type.

Fixing the NS_ERROR_DOM_DATA_CLONE_ERR Error

Once you identify which data is causing the error, you can proceed to fix it. The following approaches are the most common solutions:

1. Avoid Unsupported Data Types

If you are trying to clone data that includes functions, DOM elements, or class instances like File or Blob, you will need to remove or replace those data points before cloning:

let obj = {
  name: "Example",
  func: function() { console.log("Hello world!"); } // Function cannot be cloned
};

delete obj.func; // Remove the function that causes the error

window.postMessage(obj, "*");

2. Use JSON for Serialization and Deserialization

You can serialize the data into JSON format to ensure that unsupported data structures are not transmitted:

let obj = {
  name: "Example",
  value: 123
};

// Serialize to JSON
let jsonData = JSON.stringify(obj);

// Transfer via postMessage
window.postMessage(jsonData, "*");

// On the receiving side
let receivedData = JSON.parse(event.data);

3. Use Cloning Libraries

There are libraries that can handle cloning complex objects, such as the structuredClone() API, which allows for safe cloning, including support for cyclic references:

let obj = {
  name: "Example",
  value: 123
};

let clonedObj = structuredClone(obj); // Safe cloning of the object

window.postMessage(clonedObj, "*");

4. Store Only Serializable Parts in localStorage

If you need to store complex data structures in localStorage or sessionStorage, you must limit yourself to data types that can be serialized to JSON or only store simple types while excluding other values:

let complexObject = {
  name: "Example",
  date: new Date(), // Date object cannot be serialized to JSON
};

// Only the serializable parts of the object
let serializablePart = {
  name: complexObject.name
};

localStorage.setItem("data", JSON.stringify(serializablePart));

 

The NS_ERROR_DOM_DATA_CLONE_ERR is a result of attempting to clone data that contains unsupported structures. The best practice to avoid this error is to pay attention to the data you are cloning and utilize techniques such as JSON serialization or modern APIs like structuredClone(). By doing so, you will ensure that your application operates reliably and is not prone to data cloning issues.

By following these guidelines, you can prevent the NS_ERROR_DOM_DATA_CLONE_ERR from occurring and enhance the stability and usability of your web applications.