Add rollup's entryFileNames option

[sceniclife]

This adds this ability to specify rollup's entryFileNames configuration for the plugin.

Sometimes I want my output to have a different name than my spaEntryPoints.
Example: spaEntryPoints is "src/spa.tsx" but I would like my output to be src/index.tsx.

[webJose]

Hello, @sceniclife. Thank you for your interest in the project and your pull request.

This plug-in sets entryFileNames because the resulting entry point file name is used in the CSS-injecting algorithm. Specifically, the filename (minus the extension) is used to key a dictionary of CSS filenames. This key must be specified by the developer when calling cssLifecycleFactory. If people is allowed to freely set entryFileNames, it complicates the user experience.

Is this a problem for a particular scenario that you are trying to cover?

[sceniclife]

Hello @webJose ,

Yes, I see in the example

// IMPORTANT:  Because the file is named spa.tsx, the string 'spa'
// must be passed to the call to cssLifecycleFactory.
const cssLc = cssLifecycleFactory('spa', /* optional factory options */);

The default for spaEntryPoints is src/spa.ts , which would result in using spa for cssLifecycleFactory. If we changed from the default, the entryFileNames is [name].js, which is still valid.

In an example, I wanted the built spa to be in file index.js so that a root app can import as index.js. (say I can't change this). I can only change spaEntryPoints. If my application already has an index.ts(x), I'd have to rename that existing file in my app to something else.

---

With the PR above, I can specify spaEntryPoints to be whatever or leave it as default. Then I can set entryFileNames if needed and change the argument for cssLifecycleFactory to be the file from the build.

Lmk if there is another way to solve this

[webJose]

Hello, @sceniclife.

If you want the resulting file name to be index.js, can't you just rename the source file to index.ts?

export default defineConfig({
    plugins:[vitePluginSingleSpa({
        spaEntryPoints: ['src/index.ts']
    })],
    ...
});

The above Vite configuration will produce the bundle file index.js. Just use 'index' in your call to cssLifecycleFactory. Wouldn't this cover your need?

UPDATE: Sorry, forgot the "existing" thing: Just export from another folder:

export default defineConfig({
    plugins:[vitePluginSingleSpa({
        spaEntryPoints: ['src/spa/index.ts']
    })],
    ...
});

The above should work, right?