ReferenceError: ReadableStream is not defined
This error occurs when the JavaScript engine encounters an undefined variable or object in your code. In this case, it is indicating that the global object ReadableStream is not defined.
The ReadableStream is a built-in JavaScript class that provides a stream of data that can be read. However, it is not available in all JavaScript environments, such as older browsers.
Example
// Create a new ReadableStream
const stream = new ReadableStream();
In the above example, if the browser or JavaScript engine does not support the ReadableStream class, it will throw a ReferenceError indicating that ReadableStream is not defined.
Handling the Error
To handle this error, you can check whether the ReadableStream class is available before using it. One way to do this is by using a feature detection method:
if (typeof ReadableStream !== "undefined") {
// Create a new ReadableStream
const stream = new ReadableStream();
// Use the stream...
} else {
// Handle the case when ReadableStream is not available
console.error("ReadableStream is not supported.");
}
In the above code, the typeof ReadableStream !== "undefined" check ensures that the code inside the if statement only executes if the ReadableStream object exists in the current JavaScript environment.
If the ReadableStream class is not available, you can provide an alternative solution or display a message to the user indicating that their browser or environment does not support the required functionality.
By implementing this kind of feature detection, your code can gracefully handle cases where the ReadableStream class is not defined in the current JavaScript environment, thus avoiding the ReferenceError.