renderless.vue

<!-- MouseTracker.vue -->
<script setup>
import { ref, onMounted, onUnmounted } from 'vue'
  
const x = ref(0)
const y = ref(0)

const update = e => {
  x.value = e.pageX
  y.value = e.pageY
}

onMounted(() => window.addEventListener('mousemove', update))
onUnmounted(() => window.removeEventListener('mousemove', update))
</script>

<template>
  <slot :x="x" :y="y"/>
</template>

<!-- Usage: -->
<template>
	<MouseTracker v-slot="{ x, y }">
  	Mouse is at: {{ x }}, {{ y }}
	</MouseTracker>
</template>



<!-- 1) composable -->
<script setup>
  import { ref } from "vue";

  const checkbox = ref(false);

  const toggleCheckbox = () => {
    checkbox.value = !checkbox.value;
  };
</script>

<!--1) Usage in component -->
<template>
  <div class="comp">
    <label class="switch">
      <input type="checkbox" :value="checkbox" @click="toggleCheckbox" />
      <div class="slider rounded" :class="checkbox ? 'active' : ''"></div>
    </label>
  </div>
</template>

<script setup>
  import { useCheckboxToggle } from "./composables/useCheckboxToggle";

  const { checkbox, toggleCheckbox } = useCheckboxToggle();
</script>



<!-- 2) instead composable we can use renderless component -->
<template>
  <slot :checkbox="checkbox" :toggleCheckbox="toggleCheckbox"></slot>
</template>

<script setup>
  import { ref } from "vue";

  const checkbox = ref(false);

  const toggleCheckbox = () => {
    checkbox.value = !checkbox.value;
  };
</script>


<!--2) many different usage, depends on us and styles -->
<template>
  <slot :checkbox="checkbox" :toggleCheckbox="toggleCheckbox"></slot>
</template>

<script setup>
  import { ref } from "vue";

  const checkbox = ref(false);

  const toggleCheckbox = () => {
    checkbox.value = !checkbox.value;
  };
</script>



<!-- useFetch -->
// fetch.js
import { ref, watchEffect, toValue } from 'vue'

export function useFetch(url) {
  const data = ref(null)
  const error = ref(null)

  const fetchData = () => {
    // reset state before fetching..
    data.value = null
    error.value = null

    fetch(toValue(url))
      .then((res) => res.json())
      .then((json) => (data.value = json))
      .catch((err) => (error.value = err))
  }

  watchEffect(() => {
    fetchData()
  })

  return { data, error }
}