Using the Blob data type in JavaScript

The Blob data type in JavaScript allows efficient handling of binary data, making it useful for operations such as file uploading and downloading, image creation, and data stream management.

What is a Blob?

A Blob (Binary Large Object) is an object that represents immutable binary data. It can be used to store images, files, text, or other types of binary data.

Creating a Blob

You can create a Blob object using the Blob() constructor, which accepts an array of data and an option to specify the MIME type.

const data = new Blob(["Hello, Blob!"], { type: "text/plain" });
console.log(data);

Converting a Blob to a URL

To use a Blob as a URL in an HTML element (such as an image or file), you can use the URL.createObjectURL() method.

const blob = new Blob(["Example file"], { type: "text/plain" });
const url = URL.createObjectURL(blob);
console.log(url);

Reading a Blob

To read the content of a Blob, you can use a FileReader object.

const reader = new FileReader();
reader.onload = function(event) {
    console.log(event.target.result);
};
reader.readAsText(blob);

Downloading a Blob as a File

To enable downloading a Blob, you can create a dynamic link and simulate a click.

const link = document.createElement("a");
link.href = url;
link.download = "example.txt";
document.body.appendChild(link);
link.click();
document.body.removeChild(link);

Conclusion

JavaScript Blob objects are powerful tools for managing binary data. They offer an efficient way to work with files, images, and other content directly in the browser.