vize:croquis/cf/event-listener-leak

An event listener is registered and never removed.

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 { useWidth } from './use-width';
const width = useWidth();
</script>

<template>
<p>{{ width }}</p>
</template>

Bad

Mounting adds a window resize listener that captures the component’s width ref, but unmounting never removes it. Repeated mounts can retain unused listeners and state.

use-width.ts

import { onMounted, ref } from 'vue';
export function useWidth() {
  const width = ref(0);
  const resize = () => { width.value = window.innerWidth; };
  onMounted(() => { resize(); window.addEventListener('resize', resize); });
  return width;
}

Good

onUnmounted removes the exact same resize function registered at mount, ending that instance’s external listener lifetime.

use-width.ts

import { onMounted, onUnmounted, ref } from 'vue';
export function useWidth() {
  const width = ref(0);
  const resize = () => { width.value = window.innerWidth; };
  onMounted(() => { resize(); window.addEventListener('resize', resize); });
  onUnmounted(() => { window.removeEventListener('resize', resize); });
  return width;
}

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

Public explanation

Cross-file index