Support add importmap script into head

[eshengsky]

Is your feature request related to a problem? Please describe.

I want to add a script which type is 'importmap' into top of head, but all solution is failed. The official custom head config, will add script into end of head, this causes 'importmap' to fail to work.

Describe the solution you'd like

• add 'importmap' config in .vitepress/config
• or, let head config to support position top/end

Describe alternatives you've considered

No response

Additional context

No response

Validations

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• Read the docs.
• Read the Contributing Guidelines.
• Check that there isn't already an issue that asks for the same feature to avoid creating a duplicate.

[brc-dd]

We can move that above other scripts by default maybe 👀 But having an order attribute might be more customizable.

[mistic100]

I think importmap should have a special handling and be directly added to the HTML at compile time (even in dev mode) and not added at runtime by useUpdateHead.

When declaring a head element with ['script', { type: 'importmap' }, ``....``] I get the following error (french):

Les mappages d’importation ne sont pas autorisés après le chargement d’un module ou le démarrage du préchargement.

Which roughly transletes to

Import mapping are not autorised after a module has been loaded or after the preloading has begun.

Has I understand it, importmap scripts cannot be added dynamically to the page.

[mistic100]

Relevant vite issue vitejs/vite#15192

A working solution is privided here : use a Vite plugin to inject the importmap inside the HTML.

Example:

export default defineConfig({
    vite: {
        plugins: [
            {
                name: 'html-transform',
                transformIndexHtml(html) {
                    return html.replace('</head>', `
<script type="importmap">
{
    "imports": {
        .....
    }
}
</script>
</head>`,
                    );
                },
            },
        ],
    },
});