Async Error Handling in Composables
try/catch in async composables, error state exposure, retry logic in useFetch.
Async Error Handling in Composables is a free Vue Academy lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Vue Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Errors in Async Composables
Composables that fetch or run async work need their own error strategy. The pattern: expose an error ref so consumers can react, while the async function catches failures internally.
Exposing an error Ref
Return an error ref alongside data and loading. Consumers watch it to show messages.
function useApi() {
const data = ref(null);
const error = ref(null);
return { data, error };
}try / catch in Async Functions
Inside the async function, wrap awaited calls in try/catch and store the failure in the error ref rather than letting it throw uncaught.
async function load() {
try {
data.value = await api.get();
} catch (e) {
error.value = e;
}
}Resetting Error State
Clear the previous error at the start of each attempt so stale messages do not linger after a successful retry.
async function load() {
error.value = null;
try { /* ... */ } catch (e) { error.value = e; }
}A retryCount Ref
To support retries, track attempts with a retryCount ref. Increment it each time the user retries.
const retryCount = ref(0);
function retry() {
retryCount.value++;
load();
}Automatic Retry Logic
You can retry automatically up to a limit, backing off between attempts. Stop once the count exceeds your maximum.
async function load() {
try {
data.value = await api.get();
} catch (e) {
if (retryCount.value < 3) {
retryCount.value++;
return load();
}
error.value = e;
}
}Returning the Full API
Expose data, error, the retry function, and retryCount so the component has everything it needs.
return { data, error, retry, retryCount };Consuming the Error
In the component, render based on the error ref and offer a retry button wired to the exposed function.
<p v-if="error">Failed: {{ error.message }}</p>
<button v-if="error" @click="retry">Retry</button>Composable Error vs Global Handler
Composable-level error handling is for expected failures the UI should react to - a failed request, a validation error. The component decides how to present them.
When the Global Boundary Steps In
The global handler and error boundaries catch unexpected, unhandled errors - programming bugs, render crashes. They are the safety net, not the primary handler for predictable async failures.
Choosing the Right Layer
Rule of thumb: handle anticipated async errors inside the composable with an error ref; let truly unexpected ones bubble to the global handler. This keeps UI feedback local and crash-protection global.
Quick Check
Where should expected async failures (like a failed fetch) be handled?
Recap
You learned async composables expose an error ref, use try/catch in async functions, support retries with a retryCount ref and retry function, and that composable-level errors handle expected failures while the global handler covers unexpected ones.
Frequently asked questions
Is the “Async Error Handling in Composables” lesson free?
Yes — the full text of “Async Error Handling in Composables” is free to read here on the web, and the Vue Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Vue Academy course, upgrade to CoddyKit PRO.
What will I learn in “Async Error Handling in Composables”?
try/catch in async composables, error state exposure, retry logic in useFetch. You practise Vue Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Vue Academy?
No prior experience is required. Vue Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Async Error Handling in Composables” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Vue Academy lesson?
Yes. Every Vue Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- onErrorCaptured Lifecycle Hook
- Error Boundary Components
- app.config.errorHandler for Global Errors
- Async Error Handling in Composables