How to Fix JavaScript Error: Ready-to-Use Utilities

This collection provides practical code snippets to help you fix JavaScript error issues quickly. Each utility function is ready to copy and paste into your projects for immediate error resolution.

Safe Property Access Utilities #

These utilities help you fix JavaScript error issues related to undefined properties:

Error Boundary Wrapper Function #

A utility to wrap functions with automatic error handling:

function withErrorHandling(fn, errorCallback = console.error) {
    return function(...args) {
        try {
            return fn.apply(this, args);
        } catch (error) {
            errorCallback(`Error in ${fn.name}:`, error);
            return null;
        }
    };
}

// Usage example
const riskyFunction = function(data) {
    return data.toUpperCase(); // Will fail if data is null/undefined
};

const safeFunction = withErrorHandling(riskyFunction, (msg, error) => {
    console.log(`Caught: ${error.message}`);
});

// Test the wrapped function
console.log(safeFunction("hello")); // "HELLO"
console.log(safeFunction(null));    // null (with error logged)

Type Validation Utilities #

These functions help prevent type-related errors:

Async Error Handler #

Utility for handling asynchronous operation errors:

// Async error wrapper
async function asyncErrorWrapper(asyncFn, ...args) {
    try {
        const result = await asyncFn(...args);
        return { success: true, data: result, error: null };
    } catch (error) {
        return { success: false, data: null, error: error.message };
    }
}

// Promise-based error handler
function handlePromise(promise) {
    return promise
        .then(data => ({ success: true, data, error: null }))
        .catch(error => ({ success: false, data: null, error: error.message }));
}

// Usage examples
async function fetchData(url) {
    const response = await fetch(url);
    if (!response.ok) {
        throw new Error(`HTTP ${response.status}: ${response.statusText}`);
    }
    return response.json();
}

// Using the error wrapper
async function safeDataFetch() {
    const result = await asyncErrorWrapper(fetchData, '/api/users');
    
    if (result.success) {
        console.log('Data received:', result.data);
    } else {
        console.log('Error occurred:', result.error);
    }
}

DOM Element Safety Utilities #

Prevent DOM manipulation errors:

Array Operation Safety #

Utilities to prevent array-related errors:

JSON Parsing Safety #

Prevent JSON parsing errors with these utilities:

// Safe JSON utilities
const JSONUtils = {
    safeParse: function(jsonString, defaultValue = null) {
        try {
            return JSON.parse(jsonString);
        } catch (error) {
            console.warn('JSON parse error:', error.message);
            return defaultValue;
        }
    },
    
    safeStringify: function(object, defaultValue = '{}') {
        try {
            return JSON.stringify(object);
        } catch (error) {
            console.warn('JSON stringify error:', error.message);
            return defaultValue;
        }
    },
    
    parseWithValidation: function(jsonString, validator) {
        const parsed = this.safeParse(jsonString);
        if (parsed === null) return null;
        
        if (typeof validator === 'function' && !validator(parsed)) {
            console.warn('JSON validation failed');
            return null;
        }
        
        return parsed;
    }
};

// Usage examples
const validJSON = '{"name": "John", "age": 30}';
const invalidJSON = '{"name": "John", "age":}';

console.log("Valid:", JSONUtils.safeParse(validJSON));
console.log("Invalid:", JSONUtils.safeParse(invalidJSON, { error: true }));

Usage Tips #

1. Copy these utilities into a separate errorUtils.js file
2. Import them where needed: import { safeGet, withErrorHandling } from './errorUtils.js'
3. Customize error handling by modifying the callback functions
4. Add logging to track where errors occur in production

These utilities provide immediate solutions to fix JavaScript error issues and make your code more robust. Use them as building blocks for your error handling strategy.

For comprehensive error debugging techniques, see our Complete JavaScript Error Guide.