Specify Transition Type When Mixing CSS Transitions and Animations

Impact: MEDIUM - When you have both CSS transitions and CSS animations applied to the same element (for example, a Vue-triggered animation combined with a hover transition effect), Vue cannot automatically determine which end event to listen for. You must explicitly tell Vue which type to prioritize using the type attribute with a value of either "animation" or "transition".

Task Checklist

• [ ] Check if your element has both transition and animation CSS properties
• [ ] Determine which timing should control when Vue considers the transition complete
• [ ] Add type="animation" or type="transition" to the <Transition> component
• [ ] The type should match whichever animation/transition is longer or more important

Problematic Code:

<template>
  <!-- BAD: Both transition and animation present, Vue might pick wrong end event -->
  <Transition name="bounce">
    <div v-if="show" class="box">
      Hover me for additional effect
    </div>
  </Transition>
</template>

<style>
/* Vue-triggered CSS animation */
.bounce-enter-active {
  animation: bounce-in 0.5s;
}

.bounce-leave-active {
  animation: bounce-out 0.3s;
}

@keyframes bounce-in {
  0% { transform: scale(0); }
  50% { transform: scale(1.2); }
  100% { transform: scale(1); }
}

@keyframes bounce-out {
  0% { transform: scale(1); }
  100% { transform: scale(0); }
}

/* Additional hover transition on same element */
.box {
  transition: background-color 0.2s ease, box-shadow 0.2s ease;
}

.box:hover {
  background-color: #f0f0f0;
  box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}
</style>

Correct Code:

<template>
  <!-- GOOD: Explicitly specify that animation controls timing -->
  <Transition name="bounce" type="animation">
    <div v-if="show" class="box">
      Hover me for additional effect
    </div>
  </Transition>
</template>

<style>
/* Vue-triggered CSS animation - this is what we care about */
.bounce-enter-active {
  animation: bounce-in 0.5s;
}

.bounce-leave-active {
  animation: bounce-out 0.3s;
}

@keyframes bounce-in {
  0% { transform: scale(0); }
  50% { transform: scale(1.2); }
  100% { transform: scale(1); }
}

@keyframes bounce-out {
  0% { transform: scale(1); }
  100% { transform: scale(0); }
}

/* Additional hover transition - unrelated to Vue transition timing */
.box {
  transition: background-color 0.2s ease, box-shadow 0.2s ease;
}

.box:hover {
  background-color: #f0f0f0;
  box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}
</style>

When to Use Each Type

Use type="animation" when:

• Your enter/leave effects use @keyframes animations
• The animation is longer than any transitions
• You want precise control over multi-step animations

<Transition name="fancy" type="animation">
  <div v-if="show" class="animated-element" />
</Transition>

<style>
.fancy-enter-active {
  animation: fancy-entrance 1s ease-out;
}

.animated-element {
  /* This shorter transition should not affect timing */
  transition: color 0.2s;
}
</style>

Use type="transition" when:

• Your enter/leave effects use CSS transition property
• You have decorative animations that shouldn't affect timing

<Transition name="slide" type="transition">
  <div v-if="show" class="sliding-element" />
</Transition>

<style>
.slide-enter-active,
.slide-leave-active {
  transition: transform 0.3s ease;
}

.slide-enter-from,
.slide-leave-to {
  transform: translateX(-100%);
}

/* Decorative infinite animation should not affect timing */
.sliding-element {
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.8; }
}
</style>

Common Symptoms Without Type Specification

1. Transition ends too early (element snaps to final position)
2. Transition hangs or takes too long to complete
3. Element disappears before animation finishes
4. CSS classes remain applied after transition should be complete

Reference

• Vue.js Transition Documentation