charging-cabinet/software/h5-uniapp/agent/skills/vue-best-practices/reference/keyup-modifier-timing.md

title, impact, impactDescription, type, tags

title	impact	impactDescription	type	tags
System Modifier Keys Must Be Held During keyup Events	MEDIUM	Modifier keys (ctrl, alt, shift, meta) behave differently with keyup - they must be held when the key is released	gotcha	vue3 events keyboard modifiers keyup shortcuts

System Modifier Keys Must Be Held During keyup Events

Impact: MEDIUM - When using system modifier keys (.ctrl, .alt, .shift, .meta) with keyup events, the modifier must still be pressed when the other key is released. Releasing the modifier key first will not trigger the event, causing keyboard shortcuts to appear broken.

Task Checklist

• Understand that @keyup.ctrl requires Ctrl to be held while releasing another key
• Consider using keydown instead of keyup for modifier key combinations
• Use .exact when you need precise modifier key control
• Test keyboard shortcuts with proper key release order

Incorrect:

<!-- WRONG: Expecting this to fire when Ctrl is released -->
<template>
  <input @keyup.ctrl="onCtrlRelease" />
  <!-- This does NOT fire when you just release Ctrl! -->
  <!-- It fires when you release ANY key while holding Ctrl -->
</template>

<!-- WRONG: Misunderstanding keyup.ctrl behavior -->
<template>
  <div @keyup.ctrl="handleShortcut">
    <!-- User presses Ctrl+S, releases Ctrl first, then S -->
    <!-- Event does NOT fire because Ctrl wasn't held during S release -->
  </div>
</template>

Correct:

<!-- CORRECT: User must hold Ctrl while releasing another key -->
<template>
  <input @keyup.ctrl.s="saveDocument" />
  <!-- User presses Ctrl+S, then releases S while holding Ctrl -->
  <!-- Event fires correctly -->
</template>

<script setup>
function saveDocument(event) {
  event.preventDefault()
  // Save logic here
}
</script>

<!-- CORRECT: Use keydown for more intuitive modifier behavior -->
<template>
  <div @keydown.ctrl.s="saveDocument">
    <!-- keydown fires immediately when both keys are pressed -->
    <!-- More intuitive for keyboard shortcuts -->
  </div>
</template>

<!-- CORRECT: Use .exact for precise modifier control -->
<template>
  <!-- Only fires when ONLY Ctrl is pressed (no Shift, Alt, etc.) -->
  <button @click.ctrl.exact="onCtrlClick">Ctrl+Click Only</button>

  <!-- Fires with no system modifiers at all -->
  <button @click.exact="onPlainClick">Plain Click Only</button>
</template>

How System Modifiers Work with keyup

// Timeline of Ctrl+S keydown:
// 1. User presses Ctrl (keydown fires)
// 2. User presses S while holding Ctrl (keydown fires)

// Timeline of Ctrl+S keyup:
// 3. User releases S while holding Ctrl (keyup.ctrl.s fires!)
// 4. User releases Ctrl (keyup fires, but not keyup.ctrl.s)

// Common mistake:
// 3. User releases Ctrl first (nothing fires for our handler)
// 4. User releases S (keyup.s fires, but not keyup.ctrl.s)

System Modifier Keys

<!-- Available system modifiers -->
<input @keyup.ctrl="..." />   <!-- Ctrl key -->
<input @keyup.alt="..." />    <!-- Alt key (Option on Mac) -->
<input @keyup.shift="..." />  <!-- Shift key -->
<input @keyup.meta="..." />   <!-- Cmd on Mac, Windows key on PC -->

The .exact Modifier

<!-- Different .exact behaviors -->

<!-- Fires even if Shift/Alt are also pressed -->
<button @click.ctrl="onClick">Ctrl + any other modifiers</button>

<!-- Fires ONLY when Ctrl alone is pressed -->
<button @click.ctrl.exact="onClick">Ctrl only, no other modifiers</button>

<!-- Fires ONLY when no system modifiers are pressed -->
<button @click.exact="onClick">No modifiers allowed</button>

Best Practice: Prefer keydown for Shortcuts

<template>
  <div
    tabindex="0"
    @keydown.ctrl.s.prevent="save"
    @keydown.ctrl.z.prevent="undo"
    @keydown.ctrl.shift.z.prevent="redo"
  >
    <!-- keydown is more reliable for keyboard shortcuts -->
    <!-- Add .prevent to stop browser default (e.g., save dialog) -->
  </div>
</template>

Reference

• Vue.js Event Handling - Key Modifiers
• Vue.js Event Handling - System Modifier Keys