How do I write data to a file with Javascript?

Question

I made a game with javascript using this tutorial as a base: http://html5gamedev.samlancashire.com/making-a-simple-html5-canvas-game-part-3-drawing-images/ How do I get it to write the data from the item counter (var itemCounter = 50;) to a text file named savedata.txt? I googled it, but no helpful results came up. Can someone help me?

• Felix Kling: If you want to store the file on the client, then the answer is: you can't.
• Piotr Wu: Check this topic: link
• Tomas Ramirez Sarduy: As @FelixKling says, if the file is on the client you can't... We will need more info about what exactly are you trying to do, but you can try with Local Storage

Answer 1

Technically, you can create a server with nodejs [which is built with javascript]. Details can be found here

Answer 2

Its not possible to store the data as a file on the client. But you can use localstorage, websql, indexeddb or simply cookies for it. Note that all of these storages have different properties in terms of lifetime.

You could also create a blob using the blobapi and then create a dataurl and request the user to save it, using drag and drop + fileapi to read the data, this approach however will make it easy for users to modify the data.

Answer 3

Writing a file is posible with the new FileWriter and FileSystem APIs.

More mature solutions (not using files) have already been mentioned

Answer 4

Javascript does not support working with files, for data storage several options are available:

• cookies
• Local Storage
• Server side storage

• user3055828: I already have a file called savedata.txt. I want it to write to it, not create it.
• roo2: Updated the Answer, javascript is sandboxed preventing it from reading, writing or creating files. Although some newer APIs add this support ( see my other answer)