How to import a JS file at runtime?

[rough hearth]

I'm needing the ability to import a user-defined JS file at runtime (for app configuration via a JS file... a JSON file won't work).

I think the only way to do this currently via a custom Rust function (since the runtime JS doesn't have access to the file system). Is this correct?

If so, could anyone point me to some example code (https://www.secondstate.io/articles/embed-javascript-in-rust/ is the only thing that I've found which seems close but I'm new to Rust so may be missing something obvious)?

[proud laurel]

https://tauri.app/v1/api/js/tauri#convertfilesrc

[rough hearth]

Thanks @proud laurel. It's helpful to know about this, but ultimately I'm not seeing where this is any different than getting a JS file as plain text via a Rust function. The issue is still that I need to somehow evaluate the text into actual JavaScript. The use of eval() seems to be be blocked by Tauri's bundler (probably for good reason) but perhaps there's some other way....

[proud laurel]

the eval() doesn't work?
what error is it

[rough hearth]

[WARNING] Using direct eval with a bundler is not recommended and may cause problems [direct-eval]

You can read more about direct eval and bundling here: https://esbuild.github.io/link/direct-eval

And then the build fails saying that "no matching export" is found

[proud laurel]

I think the link contains all things that you need.

[rough hearth]

Alright, thanks for confirming... this does seem to be the case. However, I'm now seeing that trying to use an "indirect eval" it's always returning undefined (regardless of the content of the JS file)

[proud laurel]

even the content just 1?

[rough hearth]

Oh, interesting... that does work

hmm....

So window.eval('1') works but window.eval('var test = 1') does not work...

That doesn't seem right...

[proud laurel]

var test = 1 does do it things, it return undefined because you didn't return it

var test = 1; test

[rough hearth]

🤦‍♂️ that was the problem...

Thank you, @proud laurel !

[proud laurel]

if you need pass some value, I suggest you use the function method.

[rough hearth]

yes, that makes sense.

I am wondering whether it's somehow possible to support a top-level return/export

e.g.

export default { test: 123 }

or

return { test: 123 }

[proud laurel]

if use function, then the content could just be a regular function body

[rough hearth]

The first returns:

SyntaxError: Unexpected keyword 'export'

The second:

Return statements are only valid inside functions.

[proud laurel]

const func = new Function("arg1", "arg2", `
const sum = arg1 + arg2
return { result: arg1 + arg2 + sum }  
`)

console.log(func(1, 2)) // { result: 6 }

[proud laurel]

return value in eval just need put the value at end of code without ;

like

window.args = {}
window.args.arg1 = 1
window.args.arg2 = 2
console.log(window.eval(`
const sum = window.args.arg1 + window.args.arg2;
const result = { result: window.args.arg1 + window.args.arg2 + sum };
result
`)) // { result: 6 }