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JavaScript error handling

JavaScript error handling, try...catch, and custom errors

Learn JavaScript error handling with focused lessons on try...catch, throw, finally, custom Error classes, extending Error, promise rejection handling, async/await try/catch, resource loading errors, and practical recovery paths.

Error handling lessons and concepts

  1. try...catch basics

    Catch runtime errors, inspect error objects, use finally, and decide when code should recover or fail.

    Outcome: Handle synchronous failures without hiding important programming mistakes.

    • JavaScript try catch
    • error handling JavaScript
    • finally block
    Study Error handling, "try...catch"

  2. Custom errors

    Extend Error to create named error types that make validation, parsing, and application failures clearer.

    Outcome: Represent different failure types with explicit error classes.

    • custom errors JavaScript
    • extend Error
    • Error class
    Study Custom errors, extending Error

  3. Promise error handling

    Handle rejected promises, understand propagation, and place catch handlers where recovery belongs.

    Outcome: Keep asynchronous failure handling predictable in promise chains.

    • promise error handling
    • catch promise
    • rejected promise
    Study Error handling with promises

  4. async/await try...catch

    Use try/catch around awaited work and keep async functions readable when network or parsing steps fail.

    Outcome: Convert promise failures into clear sequential-looking error handling.

    • async await error handling
    • try catch await
    • async function errors
    Study Async/await

  5. Fetch and request failures

    Understand request errors, HTTP responses, aborting requests, and cross-origin failures in browser code.

    Outcome: Build browser request code that handles failed, canceled, and blocked requests deliberately.

    • fetch error handling
    • HTTP error JavaScript
    • AbortController error
    Study Fetch

  6. Resource loading errors

    Handle script, image, and resource loading failures with browser load and error events.

    Outcome: Detect asset loading failures and choose fallback behavior.

    • onerror JavaScript
    • resource loading error
    • load event error
    Study Resource loading: onload and onerror

  7. Class-based error hierarchies

    Use class inheritance patterns to build clearer custom error hierarchies for larger programs.

    Outcome: Connect class inheritance knowledge to robust failure modeling.

    • JavaScript error classes
    • class inheritance errors
    • custom Error subclass
    Study Class inheritance