built project but npm start fails

[GiulioCesare]

Hello RussCoder, my name is Giulio and I was looking into this project and tried to build and test it.
I followed the steps to build the project and everything seems fine.
But where I run "npm start" from the viewer directory I get this error in the browser:

Error: There is no DjVu object! You have to include the DjVu.js library first!
./src/DjVu.js
http://localhost:3000/static/js/main.chunk.js:18:9

15 | * Also it encapsulates the logic of getting the global DjVu object.
16 | */
17 | if (typeof DjVu !== 'object') {

18 | throw new Error("There is no DjVu object! You have to include the DjVu.js library first!");
| ^ 19 | }
20 |
21 | const djvu = DjVu; // eslint-disable-line

Plus other errors

Any idea why?

Many thanks for any help

[r-pankevicius]

I think I saw it. You need to include DjVu.js library in your main html page.

If you go to view-source:https://djvu.js.org/ then you'll see this sequence of includes:

<script src="[/assets/dist/djvu.js](view-source:https://djvu.js.org/assets/dist/djvu.js)"></script
<script src="[/assets/dist/djvu_viewer.js](view-source:https://djvu.js.org/assets/dist/djvu_viewer.js)">

djvu.js is a library, djvu_viewer.js is a viewer and .. read again: "You have to include the DjVu.js library first!"

[GiulioCesare]

Thank you r-pankevicius. The problem was that I might have missed the "npm run install" step.
I did as suggested by RussCoder and now it works.

[RussCoder]

Hello, Giulio!

That's because you started the viewer without building the library at least once.

In the root directory of the project run:

npm run install
npm run build

It will build everything. Then you can start the viewer and work only with it.
Alternatively you can build only the library, in the library folder run npm install and npm run build - the library bundle will be copied to the viewer's directory. If you want to change the library then run npm start there - the library will be recreated on each change.

The library and the viewer have separate configs, so you should either build the library once or run npm start in two consoles - one for the library and one for the viewer.

[GiulioCesare]

Thank you RussCoder for the prompt reply.
I might have missed one of the above steps.
I did as suggested and it now works.
Best regards