Prompt File Download With Xmlhttprequest

Downloading files from a web server is a common task in web development. If you want to allow users to download files from your website with a click of a button, then the Xmlhttprequest can help you achieve this easily. In this article, we will guide you through the process of prompt file download using Xmlhttprequest.

Xmlhttprequest, commonly known as XHR, is a JavaScript object that allows you to make HTTP requests from the browser. This object can be used to fetch data or files from a server asynchronously without having to reload the page. In the context of file downloads, XHR can be particularly handy as it allows you to initiate file downloads without any complex server-side logic.

To prompt a file download using Xmlhttprequest, follow these steps:

1. Create an XHR object: Start by creating a new instance of the Xmlhttprequest object. You can do this by calling the XMLHttpRequest constructor like this: `var xhr = new XMLHttpRequest();`

2. Open the connection: Use the `open` method of the XHR object to specify the type of request (GET), URL of the file you want to download, and set the asynchronous flag to true. For example: `xhr.open('GET', 'file-url', true);`

3. Set the response type: To handle the file download properly, you need to set the response type of the XHR object to 'blob' (Binary Large OBject). This ensures that the file is treated as binary data. You can set the response type like this: `xhr.responseType = 'blob';`

4. Send the request: After configuring the XHR object, you can send the request to the server using the `send` method. This will initiate the file download process. Here's how you can do it: `xhr.send();`

5. Handle the response: Once the file download request is complete, you need to handle the response to trigger the file download prompt for the user. You can achieve this by checking the XHR status and creating a new URL object with the blob data. Here's a sample code snippet to handle the response:

xhr.onload = function() {
  if (xhr.status === 200) {
    var blob = new Blob([xhr.response], {type: xhr.getResponseHeader('Content-Type')});
    var downloadUrl = URL.createObjectURL(blob);
    var a = document.createElement('a');
    a.href = downloadUrl;
    a.download = 'file-name.extension';
    a.click();
    URL.revokeObjectURL(downloadUrl);
  }
};

In the code snippet above, we create a new Blob object from the XHR response data, generate a download URL for it, create a new anchor element (``), set the download attributes, simulate a click event on the anchor element to trigger the file download prompt, and finally revoke the object URL to clean up after the download.