Dynamically add and remove classes on mouseover - Vue.js

Question

I can successfully add a class on mouseover with Vue. But I want to remove the class when the mouse leaves the element. What is the idiomatic way of handling this in Vue?

<

Answer 1

Listen for both mouseover and mouseout and set the class based on that.

console.clear()

new Vue({
  el: "#app",
  data:{
    isHovering: false
  }
})

.hovering{
  color: red
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.13/vue.js"></script>
<div id="app">
  <h1 @mouseover="isHovering = true" 
      @mouseout="isHovering = false" 
      :class="{hovering: isHovering}">
    {{ isHovering ? "Woot! Hovered" : "Hover over me" }}
  </h1>
</div>

Or just use CSS.

console.clear()

new Vue({
  el: "#app",
  data:{
    isHovering: false
  }
})

h1:hover{
  color: red
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.13/vue.js"></script>
<div id="app">
  <h1 @mouseover="isHovering = true" 
      @mouseout="isHovering = false" >
    {{ isHovering ? "Woot! Hovered" : "Hover over me" }}
  </h1>
</div>

Answer 2

A more scalable solution would be to use a directive:

// Directives
Vue.directive('add-class-hover', {
  bind(el, binding, vnode) {    
    const { value="" } = binding;
    el.addEventListener('mouseenter',()=> {
        el.classList.add(value)
    });
    el.addEventListener('mouseleave',()=> {
        el.classList.remove(value)
    });
  },
  unbind(el, binding, vnode) {
    el.removeEventListener('mouseenter');
    el.removeEventListener('mouseleave')
  }
})

new Vue({
  el: "#app"
})

.hoverClass {
color: red;
font-weight: 700;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>

<div id="app">
  <h1 v-add-class-hover="'hoverClass'">
    Text
  </h1>
</div>