How to handle errors in TypeScript



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Handling errors in TypeScript is crucial for writing robust and reliable applications. TypeScript provides several mechanisms for error handling. Here are some common ways to handle errors in TypeScript:

  1. Using try-catch blocks: TypeScript supports the standard try-catch blocks for handling exceptions. This is useful when you want to catch and handle specific types of errors.

    typescript
    try {
    // Code that may throw an error
} catch (error) {
    // Handle the error
    console.error(error);
}

  2. Throwing custom errors: You can create custom error classes by extending the built-in Error class. This allows you to throw and catch specific types of errors.

    typescript
    class CustomError extends Error {
    constructor(message: string) {
        super(message);
        this.name = 'CustomError';
    }
}

try {
    throw new CustomError('This is a custom error');
} catch (error) {
    if (error instanceof CustomError) {
        // Handle the custom error
        console.error(error.message);
    } else {
        // Handle other types of errors
        console.error(error);
    }
}

  3. Using the try-catch-finally statement: You can also use the finally block to execute code regardless of whether an exception is thrown or not.

    typescript
    try {
    // Code that may throw an error
} catch (error) {
    // Handle the error
    console.error(error);
} finally {
    // Code that will always execute
}

  4. Async/Await Error Handling: When working with asynchronous code, you can use try-catch blocks with async/await.

    typescript
    async function fetchData() {
    try {
        const result = await fetch('https://api.example.com/data');
        const data = await result.json();
        console.log(data);
    } catch (error) {
        console.error('Error fetching data:', error);
    }
}

fetchData();

  5. Using Optional Chaining and Nullish Coalescing: TypeScript 3.7 introduced optional chaining (?.) and nullish coalescing (??) operators, which can be used to handle undefined or null values more gracefully.

    typescript
    const value = someObject?.nestedObject?.property ?? 'default';

  6. Validation and Guards: Validate inputs and use type guards to ensure the correctness of your data, reducing the likelihood of runtime errors.

    typescript
    function divide(a: number, b: number): number {
    if (b === 0) {
        throw new Error('Cannot divide by zero');
    }
    return a / b;
}

These approaches provide a foundation for handling errors in TypeScript, and the choice between them depends on the specific needs and context of your application.

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