Mikuru

Mikuru is a compile-first JavaScript framework for Vue-like single-file components that generate direct DOM update code instead of using a virtual DOM.

It is intentionally small. Mikuru v1 is a practical validation release for writing .mikuru components in Vite apps, not a Vue compatibility layer.

Requirements

• Node.js 22 or newer
• Vite 8 or newer for app development

Create a New App

The fastest way to try Mikuru is the package CLI:

npx mikuru create my-app
cd my-app
npm install
npm run typecheck
npm run dev

The generated starter includes Vite, TypeScript, the package-provided .mikuru module declaration, and a welcome component at src/App.mikuru.

Use the basic template when you want a small component composition example:

npx mikuru create my-basic-app -t basic

Use the video-player template when you want a Vite app that imports the package-provided MikuruVideoPlayer component:

npx mikuru create my-video-app -t video-player

List available templates:

npx mikuru --list-templates
starter - minimal Vite app
basic - component composition example
video-player - MikuruVideoPlayer media app

Run a dry-run to preview the target, template, and files without writing them:

npx mikuru create my-app -t basic --dry-run

When run in a terminal, mikuru create asks for a project name and template if they are omitted. Use --yes / -y to skip interactive prompts and accept defaults. mikuru create also accepts --force for non-empty directories.

Generated apps include npm run typecheck for a quick TypeScript validation pass before running or building.

Add Mikuru to a Vite App

Install Mikuru and the Vite tooling:

npm install mikuru
npm install -D vite typescript

Configure Vite:

import { defineConfig } from "vite";
import { mikuru } from "mikuru/vite";

export default defineConfig({
  plugins: [mikuru()]
});

Use mikuru({ batchedUpdates: true }) to opt into queued generated DOM effects. In that mode, DOM updates triggered by refs flush through the runtime job queue and can be awaited with nextTick().

Create a .mikuru component:

<template>
  <button @click="increment">count: {{ count }}</button>
</template>

<script>
import { ref } from "mikuru";

const count = ref(0);

function increment() {
  count.value += 1;
}
</script>

<style>
button {
  font: inherit;
}
</style>

Mount it from your app entry:

import { mount } from "./App.mikuru";

const app = document.querySelector("#app");

if (!app) {
  throw new Error("Missing #app");
}

mount(app);

TypeScript Declarations

For TypeScript projects, add a local declaration file such as src/mikuru-env.d.ts that imports Mikuru's package-provided .mikuru module declaration:

import "mikuru/env";

You can use the exported component types for typed wrappers or hand-written integrations:

import type { MikuruComponent } from "mikuru/env";

type GreetingProps = {
  name: string;
};

declare const Greeting: MikuruComponent<GreetingProps>;

Supported v1 Surface

• .mikuru SFCs with <template>, <script>, and <style>
• Vite plugin support through mikuru/vite
• Template interpolation with {{ value }}
• DOM events with @click, m-on:click, inline handlers, object-form option modifiers, .prevent, .stop, .self, .once, .capture, .passive, key, mouse button, system, and .exact modifiers
• Component events with @select and .once
• Attribute bindings with normalized :class and :style, boolean/form property sync, direct/object m-bind modifiers like .prop, .attr, and .camel, plus dynamic arguments like :[name] and @[event]
• m-if, m-else-if, m-else, m-show, m-for, m-html, m-text, m-pre, m-cloak, m-once, and m-memo
• m-model for common form controls, checkbox arrays, radio groups, multiple selects, modifiers, and named child component models
• v-* directive spellings remain available as compatibility aliases for existing components and Vue-oriented migrations
• Component props, events, DOM attribute fallthrough, useAttrs, template refs, dynamic <component :is>, defineProps, defineEmits, default slots, named/dynamic slots, and slot props with simple defaults
• CSS class transitions with built-in <Transition name="fade">, m-if chains, dynamic components, class overrides, appear, mode="out-in", and <TransitionGroup> for keyed lists
• Built-in <Teleport to="#target"> for rendering content outside the current DOM position
• Built-in <AsyncBoundary :loading :fallback :delay :timeout> for grouped async loading, delayed loading UI, boundary timeouts, and retryable async failures with aggregated fallback errors
• Built-in <ErrorBoundary :fallback> for local component mount, descendant event handler, lifecycle, and cleanup fallbacks, with errorInfo, retry, reset, and :reset-key recovery
• Built-in <KeepAlive> for caching one dynamic child component with include, exclude, and max controls
• Runtime helpers including ref, isRef, unref, toRef, toRefs, reactive, readonly, lazy cached read-only and writable computed, effect with optional scheduling, queueJob/flushJobs, watch, watchEffect with cleanup callbacks, nextTick, lifecycle callbacks including KeepAlive activation hooks, provide, inject, and defineAsyncComponent with ErrorBoundary handoff and SSR loader resolution
• Routing through mikuru/router with route matching, history/hash/memory histories, guards, router context helpers, and RouterView / RouterLink across mount, SSR, and hydration
• SSR through compileSsr() and mikuru/server, covering escaped text, static and bound attributes, content directives, m-pre, m-cloak, m-if chains, m-for, async child components, props, named/default slots, scoped slot props, component tree context, Teleport collection, string and async iterable stream rendering, and router route rendering with context propagation
• Hydration through compileHydration() and hydrateRoute(), reusing existing SSR DOM while attaching events, syncing text/attributes, recovering structural mismatches with an opt-out remount fallback, hydrating component context/lifecycle hooks, m-show, DOM and component m-model, m-pre, m-cloak, initial m-if / m-for DOM, Teleport target and disabled inline content, delegating child and route components to hydrate() when available, and optionally starting router history listening after route hydration
• Style injection and <style scoped> selector rewriting for common selectors, native CSS nesting, :global(...), :deep(...), nested at-rules, and malformed CSS diagnostics
• Vite-routed component CSS for CSS Modules with <style module>, preprocessor languages such as <style lang="scss">, and project-level CSS transforms such as PostCSS when using mikuru/vite
• Content-keyed Vite style requests so .mikuru scoped CSS updates reload reliably during development instead of reusing stale virtual style modules
• Optional TypeScript template type checking with typeCheckTemplate(), compile(..., { templateTypeCheck: true }), and mikuru({ templateTypeCheck: true }), including script bindings, defineProps() constructor inference, ref unwrapping, and m-for item/index scopes
• Compile errors with filenames, line/column information, code frames, and typo suggestions for built-in attributes, directives, and modifiers
• Stable devtools diagnostics with optional generated sourceURL, v-* compatibility warnings, versioned metadata/events, component tree snapshots, compiler/style diagnostic locations and frames, and hydration warnings that include phase, component, and filename context

Package Exports

Application code usually imports from mikuru:

import { computed, ref } from "mikuru";

The Vite plugin is available from mikuru/vite:

import { mikuru } from "mikuru/vite";

The router is available from mikuru/router:

import { createRouter, createWebHashHistory, provideRouter, RouterLink, RouterView, useRoute, useRouter } from "mikuru/router";

The .mikuru TypeScript declaration is available from mikuru/env:

import "mikuru/env";

Compiler, runtime, and server entries are public for lower-level integrations:

import { compile, compileHydration, compileSsr, compileStyle } from "mikuru/compiler";
import { effect, isRef, nextTick, reactive, readonly, ref, toRef, toRefs, unref, unwrap, watch } from "mikuru/runtime";
import { hydrateRoute, renderComponentToString, renderRouteToString, renderToStream, renderToString } from "mikuru/server";
import type { MikuruAsyncBoundaryFallbackProps, MikuruErrorBoundaryFallbackProps, MikuruErrorInfo, MikuruErrorPhase } from "mikuru/runtime";

compileStyle() returns scoped CSS code plus non-throwing diagnostics. Malformed scoped CSS diagnostics include offset, line, column, and a one-line frame, and debug builds emit the same fields in compiler:warning style diagnostic events.

The package also provides the mikuru binary:

npx mikuru create my-app
npx mikuru create my-basic-app -t basic
npx mikuru create my-video-app -t video-player
npx mikuru --list-templates

Transition Example

<template>
  <button @click="open = !open">Toggle</button>
  <Transition name="fade">
    <p m-if="open">Saved changes</p>
    <p m-else>Waiting for edits</p>
  </Transition>
</template>

<script>
const open = ref(false);
</script>

<style scoped>
.fade-enter-active,
.fade-leave-active {
  transition: opacity 120ms ease, transform 120ms ease;
}

.fade-enter-from,
.fade-leave-to {
  opacity: 0;
  transform: translateY(-4px);
}
</style>

Not Included in v1

• Full Vue compatibility.

Repository Development

For local framework development:

npm install
npm run ci

Useful targeted checks:

npm run typecheck
npm test
npm run build
npm run test:create
npm run test:package
npm run test:pack
npm run test:e2e
npm run test:e2e:router-ssr-hydration
npm run test:e2e:ssr-hydration

Examples can be run from the repository root:

npm run dev:basic
npm run dev:realworld
npm run dev:dogfood
npm run dev:router-ssr-hydration
npm run dev:ssr-hydration
npm run dev:mikuru-sample
npm run dev:mikuru-vue-like

The package also includes original Mikuru components:

• MikuruVideoPlayer.mikuru: overlay video controls, configurable sizing, configurable control visibility, live mode, settings menu, div-based seeking, volume/mute, playback rate, and fullscreen controls.
• MikuruAudioPlayer.mikuru: audio playback with configurable control visibility, live mode, seeking, skip controls, volume, and mute.
• MikuruImageViewer.mikuru: image zoom, pan, rotate, reset, and fullscreen controls.
• MikuruModal.mikuru: accessible modal shell with backdrop, Escape close, slots, and close events.
• MikuruCarousel.mikuru: image carousel with arrows, dots, keyboard navigation, optional autoplay, and optional thumbnail navigation.
• MikuruToast.mikuru: fixed notification stack with timed auto-dismiss, dismiss events, and tone variants.
• MikuruDropdown.mikuru: menu button with outside-click close, Escape handling, and select events.
• MikuruToolTip.mikuru: hover/focus tooltip with configurable placement.
• MikuruProgress.mikuru: determinate and indeterminate progress indicator.
• MikuruCodeBlock.mikuru: code display with language label, line numbers, and copy action.
• MikuruTabs.mikuru: accessible tab list with controlled m-model, keyboard navigation, and slot/fallback panels.
• MikuruAccordion.mikuru: single or multiple disclosure panels with controlled m-model and slot/fallback content.
• MikuruTextInput.mikuru, MikuruTextarea.mikuru, and MikuruCheckbox.mikuru: form controls that emit update:modelValue.
• MikuruSelect.mikuru: labeled select control with normalized string/object options.
• MikuruCombobox.mikuru: searchable single-select combobox with outside-click and Escape close.
• MikuruHeader.mikuru, MikuruFooter.mikuru, and MikuruSideMenu.mikuru: app shell layout primitives with normalized navigation items and selection events.

They can be imported from the package:

<script>
import MikuruVideoPlayer from "mikuru/components/MikuruVideoPlayer";
import MikuruAudioPlayer from "mikuru/components/MikuruAudioPlayer";
import MikuruImageViewer from "mikuru/components/MikuruImageViewer";
import MikuruModal from "mikuru/components/MikuruModal";
import MikuruCarousel from "mikuru/components/MikuruCarousel";
import MikuruToast from "mikuru/components/MikuruToast";
import MikuruDropdown from "mikuru/components/MikuruDropdown";
import MikuruToolTip from "mikuru/components/MikuruToolTip";
import MikuruProgress from "mikuru/components/MikuruProgress";
import MikuruCodeBlock from "mikuru/components/MikuruCodeBlock";
import MikuruTabs from "mikuru/components/MikuruTabs";
import MikuruAccordion from "mikuru/components/MikuruAccordion";
import MikuruTextInput from "mikuru/components/MikuruTextInput";
import MikuruTextarea from "mikuru/components/MikuruTextarea";
import MikuruCheckbox from "mikuru/components/MikuruCheckbox";
import MikuruSelect from "mikuru/components/MikuruSelect";
import MikuruCombobox from "mikuru/components/MikuruCombobox";
import MikuruHeader from "mikuru/components/MikuruHeader";
import MikuruFooter from "mikuru/components/MikuruFooter";
import MikuruSideMenu from "mikuru/components/MikuruSideMenu";
</script>

Documentation

• CHANGELOG.md lists published package changes.
• docs/npm-usage.md shows a manual Vite setup for package consumers.
• docs/mikuru-components.md shows usage examples for package-exported Mikuru components.
• docs/app-architecture.md describes how to keep larger Mikuru apps split across components, API modules, stores, forms, auth, and tests.
• docs/router.md documents the runtime router.
• docs/production-readiness.md summarizes debugging, parser, package, SSR, and hydration caveats.
• docs/v1-api-contract.md describes the v1 compatibility boundary used by this repository.