ref, reactive, computed and setup().
✍️ 3 exercises + code challenge in this lessonThe Composition API organises logic by feature instead of by option type. It is the recommended style for new projects (in .vue files with <script setup>).
ref(0): a reactive value; read and write it with .value in JavaScript.reactive({...}): a reactive object.computed(() => ...), watch(), onMounted()Mastering Vue Composition API helps you write clean and reliable Vue.js code. Follow standard conventions, test edge cases, and keep logic simple. Try running the code example below and complete the exercises to build confidence.
<script src="https://unpkg.com/vue@3.5.12/dist/vue.global.prod.js"></script>
<div id="app">
<p>{{ count }} × 2 = {{ double }}</p>
<button @click="count++">Increase</button>
</div>
<script>
const { createApp, ref, computed } = Vue;
createApp({
setup() {
const count = ref(1);
const double = computed(() => count.value * 2);
return { count, double };
}
}).mount("#app");
</script>Check what you learned in “Vue Composition API”.
Create a reactive value with the Composition API.
const count = (0);
In JavaScript, how do you read a ref's value?
Using setup(), create a ref name = "Vue 3" and return it so the <p> shows it.
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