JavaScript Async Await forEach Loop Solutions Utilities

These utilities solve the common problem of why does javascript async await not work with foreach loop solutions. Use these ready-to-implement functions to handle async operations in arrays correctly.

Sequential Async forEach Utility #

Process array items one by one, waiting for each to complete:

Parallel Async Processing Utility #

Process all items simultaneously for better performance:

// Parallel async processing utility
Array.prototype.forEachParallel = async function(callback, thisArg) {
    const promises = this.map((item, index) => 
        callback.call(thisArg, item, index, this)
    );
    await Promise.all(promises);
};

// Usage example
const urls = ['api/users', 'api/posts', 'api/comments'];

await urls.forEachParallel(async (url) => {
    const response = await fetch(url);
    const data = await response.json();
    console.log(`Fetched ${data.length} items from ${url}`);
});

console.log('All requests completed in parallel');

Batch Processing Utility #

Process items in batches to control load and avoid rate limiting:

Async Map with Error Handling #

Safe async mapping with comprehensive error handling:

// Async map utility with error handling
Array.prototype.mapAsync = async function(callback, options = {}) {
    const { 
        parallel = true, 
        stopOnError = false,
        defaultValue = null 
    } = options;
    
    if (parallel) {
        const promises = this.map(async (item, index) => {
            try {
                return await callback(item, index, this);
            } catch (error) {
                if (stopOnError) throw error;
                console.warn(`Error processing item ${index}:`, error.message);
                return defaultValue;
            }
        });
        return await Promise.all(promises);
    } else {
        const results = [];
        for (let i = 0; i < this.length; i++) {
            try {
                const result = await callback(this[i], i, this);
                results.push(result);
            } catch (error) {
                if (stopOnError) throw error;
                console.warn(`Error processing item ${i}:`, error.message);
                results.push(defaultValue);
            }
        }
        return results;
    }
};

Rate-Limited Async Processing #

Control the rate of async operations to respect API limits:

Async Filter Utility #

Filter arrays asynchronously based on async conditions:

// Async filter utility
Array.prototype.filterAsync = async function(callback) {
    const results = await this.mapAsync(callback);
    return this.filter((_, index) => results[index]);
};

// Usage example
const users = [
    { id: 1, name: 'John' },
    { id: 2, name: 'Jane' },
    { id: 3, name: 'Bob' }
];

const activeUsers = await users.filterAsync(async (user) => {
    // Simulate checking if user is active
    const isActive = await checkUserStatus(user.id);
    return isActive;
});

console.log('Active users:', activeUsers);

Complete Async Array Utilities Collection #

A comprehensive utility object with all async array methods:

const AsyncArrayUtils = {
    // Sequential processing
    async forEachSequential(array, callback) {
        for (let i = 0; i < array.length; i++) {
            await callback(array[i], i, array);
        }
    },
    
    // Parallel processing
    async forEachParallel(array, callback) {
        const promises = array.map(callback);
        await Promise.all(promises);
    },
    
    // Batch processing
    async forEachBatch(array, callback, batchSize = 5) {
        for (let i = 0; i < array.length; i += batchSize) {
            const batch = array.slice(i, i + batchSize);
            await Promise.all(batch.map(callback));
        }
    },
    
    // Rate-limited processing
    async forEachWithDelay(array, callback, delay = 1000) {
        for (let i = 0; i < array.length; i++) {
            await callback(array[i], i, array);
            if (i < array.length - 1) {
                await new Promise(resolve => setTimeout(resolve, delay));
            }
        }
    }
};

// Usage
await AsyncArrayUtils.forEachSequential(items, processItem);
await AsyncArrayUtils.forEachParallel(items, processItem);
await AsyncArrayUtils.forEachBatch(items, processItem, 3);

Usage Examples #

These utilities solve why does javascript async await not work with foreach loop solutions by providing proper async handling:

// Instead of broken forEach
items.forEach(async (item) => {
    await processItem(item); // Won't wait properly
});

// Use these solutions
await items.forEachAsync(async (item) => {
    await processItem(item); // Waits properly
});

// Or parallel processing
await items.forEachParallel(async (item) => {
    await processItem(item); // All run simultaneously
});

These utilities provide robust solutions for handling async operations in arrays, ensuring your code behaves predictably and efficiently.

For more async patterns, check out our Async/Await Error Guide and Promise Handling Utilities.