Indesign (IDML file) Viewer using HTML5 and Javascript

I’m working on IDML file automation. My requirement is to showcase an IDML template in an HTML5 editor.

I have a simple TextFrame with Hello World text. I saved the file as: sample.idml. Then, I unzipped sample.idml and got a few files. Went to the stories folder and opened: story_d8.xml.

Since I’m a developer, I did this using Java and exposed the file path as a REST call. The biggest stopping point is: the jQuery/AngularJS script is saying:invalid file.

Can someone suggest options to address the points below:

1. Get Content data using JavaScript (jQuery/AngularJS)
2. Put "Demo Hello" in the Content and regenerate story_d8.xml (using JavaScript)
3. Is this the correct approach? Are there alternative to this approach?

Note: My Requirement is to modifying IDML file at client side (javascript) only.