Loading local files with Javascript without a web server

Question

I need to write a software that uses HTML5 and canvas.

The whole software should be able to run locally, without the need of a server. So I'm only able to use Javascript, no php.

The difficult part: I have to dynamically fetch the content of text-files which are needed during operation.

For example: When the software starts, I need the "config.json". And after the user made some desicions, I need "story1.txt" or "story2.txt" and so on.

My Problem:

I can't use Ajax, because Chrome blocks it - local Files aren't allowed to fetch other files' content. I always get an error-Message.

What I've tried so far:

• Load Files with Ajax & jQuery

  Chrome doesn't allow me to load the file

• Load File into script-Tag

  Even if I declare the JSON-File as js-Code, I can't access the content of the loaded File

• Load File into invisible Iframe, and read its content

  Loading works, and I can see the code. But when I try to access the IFrame's content, I get the Chrome Error-Message again:

  "Uncaught SecurityError: Blocked a frame with origin "null" from accessing a frame with origin "null". Protocols, domains, and ports must match." 

Question:

Is there a way to load a Textfile dynamically, or am I forced to use a Webserver?

Answer 1

If you insist on using Chrome, it have some command line flags to allow access to/from local originated files (--allow-file-access-from-files / --disable-web-security). Do note that you need to run entire browser from scratch with those flags - i.e. if there's already any other Chrome windows open flags WON'T have any effect and that effect persists across ALL windows until Chrome is closed, which is, obviously huge hole in security.

You can set up a lightweight local server if you pack your "application" with some kind of automated setup script. This is still not very good, because you'd need to install executable that user might not want or even be completely unable to install due to restrictions.

You can pack your HTML/JS-based app as Chrome extension - extensions have much wider permissions than random code, but then you'd need to either distribute it through Google Play or provide instructions to manually install extensions for your users.

And finally, you can format all the data, including your configuration and text files your mentioned as valid JavaScript code - i.e. pack a story1.txt to story1.js like:

var myapp.story1 = "Complete text of story1.txt" 

and then just dynamically select stuff you need from corresponding vars or even use DOM manipulation to only load scripts you need through dynamically adding <script> tags. In my opinion that would be best option because it is less intrusive: it doesn't requires any installation/reconfiguration, it just works out-of-box.