vize:croquis/cf/closure-captures-reactive

A closure captures a reactive value and will not see later updates.

Default severity: Not emitted
Applies to: Analyzed component graph and the supported facts described below
Automatic fix: None; review related files and apply the repair
Options: No per-code options; supported CLI findings accept severity overrides

This is a published diagnostic contract without a current producer. The Bad/Good scenario below explains the risk and repair; no flag currently makes this code trigger.

Shared project files

Use these unchanged files in both Bad and Good. Install the imported packages in the project: Vue, plus vue-router or Pinia where shown. Follow any version-specific support note. The entry root makes the component relationship explicit.

main.ts

import { createApp } from 'vue';
import App from './App.vue';
createApp(App).mount('#app');

index.html

<!doctype html>
<html lang="en"><head><meta charset="UTF-8"><title>Contract scenario</title></head>
<body><div id="app"></div><script type="module" src="/main.ts"></script></body></html>

App.vue

<script setup lang="ts">
import { computed, ref } from 'vue';
import { makeReader } from './reader';
const count = ref(0);
const read = makeReader(count);
const shown = computed(read);
</script>

<template>
<button @click="count++">Increment {{ count }}</button><p>{{ shown }}</p>
</template>

Bad

makeReader copies count.value before creating the closure. The computed reader then returns that initial number without reading a reactive dependency.

reader.ts

import type { Ref } from 'vue';
export function makeReader(count: Ref<number>): () => number {
  const captured = count.value;
  return () => captured;
}

Good

The closure reads count.value when invoked, so the computed getter can track the ref and update shown after increments.

reader.ts

import type { Ref } from 'vue';
export function makeReader(count: Ref<number>): () => number {
  return () => count.value;
}

The Good files demonstrate the change described above; other diagnostics can still apply to the complete project.

Public explanation

Cross-file index