Why might `catch` not trigger when a promise fails, and how can I ensure proper error handling in async functions?

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This question explores JavaScript and addresses practical considerations related to: Why might `catch` not trigger when a promise fails, and how can I ensure proper error handling in async functions?

Q&A Network · Accepted Answer

When using promises in JavaScript, the `catch` block might not trigger if the promise is not properly rejected or if errors are not propagated correctly. To ensure proper error handling in async functions, always handle both resolved and rejected states of promises.

// Example of proper error handling in an async function
        async function fetchData(url) {
            try {
                const response = await fetch(url);
                if (!response.ok) {
                    throw new Error("Network response was not ok");
                }
                const data = await response.json();
                return data;
            } catch (error) {
                console.error("Error fetching data:", error);
                throw error; // Re-throw the error for further handling
            }
        }

// Usage
        fetchData("https://api.example.com/data")
            .then(data => console.log("Data received:", data))
            .catch(error => console.error("Error in promise chain:", error));

ADDITIONAL COMMENT:
- Ensure that any errors in the `try` block are thrown using "throw new Error" or similar.
- Always include a `catch` block in the promise chain to handle any errors that propagate from the async function.
- Re-throw errors in the `catch` block if you want them to be handled further up the call stack.
- Check the response status when dealing with network requests to ensure proper error handling.

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Why might `catch` not trigger when a promise fails, and how can I ensure proper error handling in async functions?

Asked on Oct 24, 2025

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