Download File From Bytes In Javascript

When working with files in JavaScript, there may be times when you need to download a file directly from bytes rather than a URL. This process can be quite handy when you're dealing with data that has been processed or modified within your code. In this article, we will explore how you can easily download a file from bytes in JavaScript.

To download a file from bytes, we'll be leveraging the `Blob` and `URL.createObjectURL` APIs. First, you'll need to have the file data available as a byte array. You can obtain this data through various means such as reading a file, receiving it over a network, or generating it within your code.

Once you have your file data in a byte array, you can create a `Blob` object by passing the byte array along with the file type as arguments. Here's an example:

function downloadFileFromBytes(byteArray, fileName, fileType) {
    const blob = new Blob([byteArray], { type: fileType });
    const url = URL.createObjectURL(blob);

    const a = document.createElement('a');
    a.href = url;
    a.download = fileName;
    a.click();

    URL.revokeObjectURL(url);
}

In the `downloadFileFromBytes` function above, we create a `Blob` object using the byte array and the specified file type. We then create a temporary URL for the `Blob` using `URL.createObjectURL`. Next, we dynamically create an anchor element (``) and set the `href` attribute to our temporary URL. We also assign the desired file name to the `download` attribute. Finally, we simulate a click on the anchor element to trigger the file download.

const byteArray = [72, 101, 108, 108, 111]; // Example byte array
const fileName = 'hello.txt';
const fileType = 'text/plain';

downloadFileFromBytes(byteArray, fileName, fileType);