Read file stream in javascript

The File object contains a number of metadata properties about the file. Most browsers provide the file name, the size of the file, and the MIME type, though depending on the platform, different browsers may provide different, or additional information. You can see this in action in the input-type-file Glitch demo. To read a file, use FileReader , which enables you to read the content of a File object into memory. The example above reads a File provided by the user, then converts it to a data URL, and uses that data URL to display the image in an img element.

Check out the read-image-file Glitch to see how to verify that the user has selected an image file. When reading large files, it may be helpful to provide some UX to indicate how far the read has progressed. For that, use the progress event provided by FileReader. The progress event provides two properties, loaded , the amount read, and total , the total amount to read.

Hero image by Vincent Botta from Unsplash. We should make sure we have Node installed to use this method. We can check that by typing node -v in the terminal or command prompt.

We create a file, app. Since the readline module is built into Node. We can use the fs module to create a readable stream. It is because the readline module is only compatible with Readable Streams.

Where would you like to share this to? Twitter Reddit Hacker News Facebook. Share link Tutorial share link. Sign Up. DigitalOcean home. Community Control Panel. Hacktoberfest Contribute to Open Source. Assuming HTML 5 solution wouldn't work cross-browser yet or doesn't do what you need.

Nikki Well, in order to solve this problem, yes. I have accepted I'm probably going to have to send content to the server to make it send it back to me the original content for this file is coming from a silverlight control — tim.

I think you can do that with silverlight. Show 1 more comment. Active Oldest Votes. Improve this answer. Michael Mior Michael Mior I'm not quite sure how this gets me to being able to put contents of my current page into a "save or open as a new file on my computer" box? I may be being stupid here likely , but I can't see it. You can easily access the contents of the current page via JavaScript.

Add a comment. Phil Phil And this is way better than those crappy Flash alternatives you see everywhere.

It doesn't allow javascript to interact with the file contents, which I think is what the OP wants. Do that and you've officially written your first cloud computing app! Daniel - this question is 4 years old.

In the file api did not enjoy good browser support, and support for ie6 and ie7 was still required for most web apps. It's a whole different game today. Gabe Moothart Gabe Moothart