How To Make A Browser Display A Save As Dialog So The User Can Save The Content Of A String To A File On His System

Ever wondered how to make a browser display a "Save As" dialog so the user can save the content of a string to a file on their system? It's actually quite simple with a few lines of code. In this article, I'll walk you through the steps to achieve this in your web application.

To begin, you'll need to create a new Blob object in JavaScript that represents the data you want to save. The Blob object allows you to store binary data and can be used to create files on the fly in the browser.

Here's an example of creating a Blob object containing a string:

const data = "Hello, world!";
const blob = new Blob([data], { type: 'text/plain' });

In this code snippet, we first define the data we want to save, which is a simple string, "Hello, world!". We then create a new Blob object using the data and specify the type as 'text/plain' since our content is plain text.

Next, we will create a URL for this Blob object using the `URL.createObjectURL` method. This URL will be used to trigger the "Save As" dialog in the browser.

const url = URL.createObjectURL(blob);

Then, we create an element in the DOM to act as a link for the user to download the file. We set the `href` attribute of the element to the URL we generated earlier and trigger a click event on the link to prompt the browser to display the "Save As" dialog.

const a = document.createElement('a');
a.href = url;
a.download = 'file.txt'; // Specify the filename for the downloaded file
a.click();

In this code snippet, we've created a new element, set its `href` attribute to the Blob object's URL, specified the filename for the downloaded file using the `download` attribute, and triggered a click event on the link. This will prompt the user to save the file with the specified filename.

URL.revokeObjectURL(url);