Modern JavaScript (ES2020)

Promise.allSettled()

Wait for all promises - don't stop on failures!

Find videos you like?

Save to resource drawer for future reference!

What is Promise.allSettled()?

Promise.allSettled() is like a patient waiter! Unlike Promise.all() which stops at the first rejection, allSettled() waits for ALL promises to complete - whether they succeed or fail - and gives you all the results!

Problem with Promise.all()

Promise.all() rejects immediately when ANY promise fails, so you lose results from successful promises. allSettled() gives you all results!

Example 1: Compare with Promise.all()

See the difference in behavior

javascript

code

DarkEditable

// Promises with mixed results
const promise1 = Promise.resolve('Success 1');
const promise2 = Promise.reject('Failed!');
const promise3 = Promise.resolve('Success 3');

// Promise.all() - stops at first rejection
Promise.all([promise1, promise2, promise3])
  .then(results => console.log('All:', results))
  .catch(error => console.log('All Error:', error));
// All Error: Failed! ❌
// Lost Success 1 and Success 3!

// Promise.allSettled() - waits for all
Promise.allSettled([promise1, promise2, promise3])
  .then(results => {
    console.log('AllSettled:', results);
  });
// AllSettled: [
//   { status: 'fulfilled', value: 'Success 1' },
//   { status: 'rejected', reason: 'Failed!' },
//   { status: 'fulfilled', value: 'Success 3' }
// ] ✅ Got all results!

// Filter successful results
Promise.allSettled([promise1, promise2, promise3])
  .then(results => {
    const successful = results
      .filter(r => r.status === 'fulfilled')
      .map(r => r.value);
    
    console.log('Successful:', successful);
    // ['Success 1', 'Success 3']
    
    const failed = results
      .filter(r => r.status === 'rejected')
      .map(r => r.reason);
    
    console.log('Failed:', failed);
    // ['Failed!']
  });

Console Output

Click "Run Code" to see output here...

Example 2: Real-World - Multiple API Calls

Fetch from multiple APIs, handle partial failures

javascript

code

DarkEditable

// Fetch data from multiple sources
async function fetchMultipleSources() {
  const urls = [
    'https://api.github.com/users/octocat',
    'https://invalid-url.com/data',  // Will fail
    'https://api.github.com/users/torvalds'
  ];
  
  const promises = urls.map(url => 
    fetch(url).then(res => res.json())
  );
  
  const results = await Promise.allSettled(promises);
  
  results.forEach((result, index) => {
    if (result.status === 'fulfilled') {
      console.log(`URL ${index}: Success`, result.value.login);
    } else {
      console.log(`URL ${index}: Failed`, result.reason.message);
    }
  });
}

fetchMultipleSources();
// URL 0: Success octocat
// URL 1: Failed fetch failed
// URL 2: Success torvalds

// Process partial results
async function getUserData(userIds) {
  const promises = userIds.map(id => 
    fetch(`/api/users/${id}`).then(r => r.json())
  );
  
  const results = await Promise.allSettled(promises);
  
  const data = {
    successful: results
      .filter(r => r.status === 'fulfilled')
      .map(r => r.value),
    failed: results
      .filter(r => r.status === 'rejected')
      .map((r, i) => ({ id: userIds[i], error: r.reason }))
  };
  
  console.log(`Loaded ${data.successful.length} users`);
  console.log(`Failed to load ${data.failed.length} users`);
  
  return data;
}

Console Output

Click "Run Code" to see output here...

Key Takeaways

⏳

Waits for All

Never rejects - waits for every promise to settle

📊

All Results

Returns array with status and value/reason for each

✅

Fulfilled

{status: 'fulfilled', value}

❌

Rejected

{status: 'rejected', reason}

Previous Topic

BigInt

Working with arbitrarily large integers beyond Number.MAX_SAFE_INTEGER (ES2020).

Next Topic

Dynamic Import

import() for lazy loading modules and code splitting (ES2020).

Ask a Question

Have a question about Promise.allSettled? Ask our AI assistant.

🔐 Login to use AI Assistant

JavaScript Code Editor

Write and experiment with JavaScript code.

Output

Click "Run Code" to see the output.

Modern JavaScript (ES2020)

Promise.allSettled()

Wait for all promises - don't stop on failures!

Find videos you like?

Save to resource drawer for future reference!

What is Promise.allSettled()?

Problem with Promise.all()

Promise.all() rejects immediately when ANY promise fails, so you lose results from successful promises. allSettled() gives you all results!

Example 1: Compare with Promise.all()

See the difference in behavior

javascript

code

DarkEditable

// Promises with mixed results
const promise1 = Promise.resolve('Success 1');
const promise2 = Promise.reject('Failed!');
const promise3 = Promise.resolve('Success 3');

Console Output

Click "Run Code" to see output here...

Example 2: Real-World - Multiple API Calls

Fetch from multiple APIs, handle partial failures

javascript

code

DarkEditable

fetchMultipleSources();
// URL 0: Success octocat
// URL 1: Failed fetch failed
// URL 2: Success torvalds

Console Output

Click "Run Code" to see output here...

Key Takeaways

⏳

Waits for All

Never rejects - waits for every promise to settle

📊

All Results

Returns array with status and value/reason for each

✅

Fulfilled

{status: 'fulfilled', value}

❌

Rejected

{status: 'rejected', reason}

Coder Pod - Learn Programming Online | AI Coding Tutor & Interview Practice

BigInt

Dynamic Import

JavaScript Code Editor

Building Your Learning Module...

Promise.allSettled()

What is Promise.allSettled()?

Problem with Promise.all()

Example 1: Compare with Promise.all()

Example 2: Real-World - Multiple API Calls

Key Takeaways

Waits for All

All Results

Fulfilled

Rejected

BigInt

Dynamic Import

JavaScript Code Editor

Promise.allSettled()

What is Promise.allSettled()?

Problem with Promise.all()

Example 1: Compare with Promise.all()

Example 2: Real-World - Multiple API Calls

Key Takeaways

Waits for All

All Results

Fulfilled

Rejected