Intermediate LevelVue JS
How do you implement asynchronous computed properties in Vue 3 without external libraries?
❓ Interview Prompt: Why computed() cannot be async and implementing async computed patterns using ref + watchEffect.
Standard 'computed()' functions must be synchronous and pure; returning a Promise from a computed property results in the ref evaluating to a Promise object instead of the resolved data!
Async Computed Pattern:
Combine a 'ref(null)' with 'watchEffect(async () => {...})':
1
Declare a ref for storing the resolved asynchronous result.
2
Inside 'watchEffect()', execute the async fetch and assign the resolved payload to the ref!
Code Implementation Example
javascript
import { ref, watchEffect } from 'vue';
const userId = ref(1);
const userAsyncData = ref(null);
// Async Computed Pattern using watchEffect
watchEffect(async () => {
const res = await fetch(`/api/users/${userId.value}`);
userAsyncData.value = await res.json();
});💡Implementing asynchronous computed data resolution using ref and watchEffect.
🎯 Interview Key Takeaway
Standard computed() cannot be async. Combine ref() with watchEffect(async () => {...}) to implement async computed patterns.
#async computed#watchEffect#Intermediate
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