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Diff for: ‎README.md

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# javascript-questions-pro (580 questions)
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# javascript-questions-pro (590 questions)
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## [Levels](./level/) (3)
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## [Levels](./level/) (4)
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- [basic](./level/basic)
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- [intermediate](./level/intermediate)
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- [advanced](./level/advanced)
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- [beginner](./level/beginner)
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## [Themes](./theme/) (209)
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## [Themes](./theme/) (211)
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- [indexeddb](./theme/indexeddb)
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- [db](./theme/db)
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- [storage](./theme/storage)
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- [verification](./theme/verification)
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- [alerts](./theme/alerts)
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- [headless testing](./theme/headless_testing)
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- [async await](./theme/async_await)
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- [express js](./theme/express_js)
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## [Tutorials with Videos](./video/) (191)
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- [What is IndexedDB](https://www.tiktok.com/@jsmentoring/photo/7448276165661314336)
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---
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### How to catch errors in Promises
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You can handle errors in promises by appending a `.catch()` method to the promise chain.
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```javascript
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fetch('https://api.example.com/data')
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.then(response => response.json())
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.then(data => console.log(data))
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.catch(error => console.error('Error:', error));
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```
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**Tags**: [beginner](./level/beginner), [JavaScript](./theme/javascript), [Promises](./theme/promises), [Error Handling](./theme/error_handling)
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---
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### How to catch errors in async/await
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Wrap your async code in a try/catch block to handle errors gracefully.
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```javascript
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async function fetchData() {
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try {
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const response = await fetch('https://api.example.com/data');
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const data = await response.json();
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console.log(data);
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} catch (error) {
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console.error('Error:', error);
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}
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}
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fetchData();
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```
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**Tags**: [intermediate](./level/intermediate), [JavaScript](./theme/javascript), [Async/Await](./theme/async_await), [Error Handling](./theme/error_handling)
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---
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### How to catch errors in synchronous code
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For synchronous operations, use a try/catch block to handle errors.
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```javascript
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try {
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const result = riskyOperation();
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console.log(result);
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} catch (error) {
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console.error('Caught an error:', error);
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}
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```
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**Tags**: [beginner](./level/beginner), [JavaScript](./theme/javascript), [Error Handling](./theme/error_handling)
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---
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### How to catch errors in event handlers
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Wrap event handler code in a try/catch block to ensure errors do not crash the application.
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```javascript
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document.getElementById('myButton').addEventListener('click', () => {
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try {
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// Code that might throw an error
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performAction();
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} catch (error) {
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console.error('Error during click event:', error);
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}
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});
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```
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**Tags**: [intermediate](./level/intermediate), [JavaScript](./theme/javascript), [Error Handling](./theme/error_handling), [Events](./theme/events)
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---
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### How to catch errors with the Fetch API
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Use `.catch()` to handle errors when making HTTP requests with the Fetch API.
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```javascript
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fetch('https://api.example.com/data')
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.then(response => {
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if (!response.ok) {
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throw new Error('Network response was not ok');
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}
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return response.json();
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})
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.then(data => console.log(data))
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.catch(error => console.error('Fetch error:', error));
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```
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**Tags**: [beginner](./level/beginner), [JavaScript](./theme/javascript), [Fetch API](./theme/fetch_api), [Error Handling](./theme/error_handling)
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---
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### How to catch errors in Node.js
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In Node.js, use try/catch for synchronous code and attach error listeners for asynchronous code.
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```javascript
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// Synchronous error handling
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try {
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const data = fs.readFileSync('/path/to/file');
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console.log(data);
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} catch (error) {
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console.error('Error reading file:', error);
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}
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// Asynchronous error handling
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fs.readFile('/path/to/file', (error, data) => {
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if (error) {
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return console.error('Error reading file:', error);
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}
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console.log(data);
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});
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```
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**Tags**: [intermediate](./level/intermediate), [JavaScript](./theme/javascript), [Node.js](./theme/node_js), [Error Handling](./theme/error_handling)
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---
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### How to catch errors in callbacks
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When working with callbacks, ensure that errors are passed as the first argument to the callback function.
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```javascript
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function performAsyncOperation(callback) {
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// Simulate error
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const error = new Error('Something went wrong');
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callback(error, null);
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}
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performAsyncOperation((error, result) => {
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if (error) {
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return console.error('Callback error:', error);
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}
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console.log(result);
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});
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```
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**Tags**: [intermediate](./level/intermediate), [JavaScript](./theme/javascript), [Callbacks](./theme/callbacks), [Error Handling](./theme/error_handling)
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---
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### How to use global error handling with try/catch
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For comprehensive error handling, set up global error listeners in your application.
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```javascript
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window.onerror = function(message, source, lineno, colno, error) {
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console.error('Global error caught:', message, 'at', source + ':' + lineno + ':' + colno);
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};
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// Example triggering a global error
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nonExistentFunction();
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```
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**Tags**: [advanced](./level/advanced), [JavaScript](./theme/javascript), [Error Handling](./theme/error_handling)
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---
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### How to catch errors in Express.js
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Use middleware to catch and handle errors in your Express applications.
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```javascript
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const express = require('express');
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const app = express();
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// Your routes here
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app.get('/', (req, res) => {
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throw new Error('Oops!');
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});
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// Error handling middleware
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app.use((err, req, res, next) => {
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console.error(err.stack);
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res.status(500).send('Something broke!');
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});
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app.listen(3000, () => console.log('Server running on port 3000'));
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```
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**Tags**: [intermediate](./level/intermediate), [JavaScript](./theme/javascript), [Express.js](./theme/express_js), [Error Handling](./theme/error_handling)
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---
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### How to catch unhandled promise rejections
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Listen for unhandled promise rejections to prevent unexpected application crashes.
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```javascript
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process.on('unhandledRejection', (reason, promise) => {
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console.error('Unhandled Rejection at:', promise, 'reason:', reason);
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});
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// Example of an unhandled rejection
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Promise.reject(new Error('Unhandled error'));
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```
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**Tags**: [advanced](./level/advanced), [JavaScript](./theme/javascript), [Promises](./theme/promises), [Error Handling](./theme/error_handling)
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---

Diff for: ‎level/advanced/how_to_catch_unhandled_promise_rejections.md

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## [How to catch unhandled promise rejections](#how-to-catch-unhandled-rejections)
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### How to catch unhandled promise rejections
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Listen for unhandled promise rejections to prevent unexpected application crashes.
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```javascript
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process.on('unhandledRejection', (reason, promise) => {
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console.error('Unhandled Rejection at:', promise, 'reason:', reason);
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});
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// Example of an unhandled rejection
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Promise.reject(new Error('Unhandled error'));
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```
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**Tags**: [advanced](./level/advanced), [JavaScript](./theme/javascript), [Promises](./theme/promises), [Error Handling](./theme/error_handling)
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Diff for: ‎level/advanced/how_to_use_global_error_handling_with_try_catch.md

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## [How to use global error handling with try/catch](#how-to-use-global-error-handling-with-try-catch)
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### How to use global error handling with try/catch
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For comprehensive error handling, set up global error listeners in your application.
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```javascript
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window.onerror = function(message, source, lineno, colno, error) {
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console.error('Global error caught:', message, 'at', source + ':' + lineno + ':' + colno);
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};
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// Example triggering a global error
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nonExistentFunction();
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```
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**Tags**: [advanced](./level/advanced), [JavaScript](./theme/javascript), [Error Handling](./theme/error_handling)
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Diff for: ‎level/beginner/how_to_catch_errors_in_promises.md

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## [How to catch errors in Promises](#how-to-catch-errors-in-promises)
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### How to catch errors in Promises
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You can handle errors in promises by appending a `.catch()` method to the promise chain.
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```javascript
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fetch('https://api.example.com/data')
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.then(response => response.json())
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.then(data => console.log(data))
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.catch(error => console.error('Error:', error));
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```
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**Tags**: [beginner](./level/beginner), [JavaScript](./theme/javascript), [Promises](./theme/promises), [Error Handling](./theme/error_handling)
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Diff for: ‎level/beginner/how_to_catch_errors_in_synchronous_code.md

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## [How to catch errors in synchronous code](#how-to-catch-errors-in-synchronous-code)
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### How to catch errors in synchronous code
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For synchronous operations, use a try/catch block to handle errors.
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```javascript
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try {
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const result = riskyOperation();
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console.log(result);
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} catch (error) {
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console.error('Caught an error:', error);
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}
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```
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**Tags**: [beginner](./level/beginner), [JavaScript](./theme/javascript), [Error Handling](./theme/error_handling)
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Diff for: ‎level/beginner/how_to_catch_errors_with_the_fetch_api.md

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## [How to catch errors with the Fetch API](#how-to-catch-errors-with-fetch-api)
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### How to catch errors with the Fetch API
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Use `.catch()` to handle errors when making HTTP requests with the Fetch API.
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```javascript
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fetch('https://api.example.com/data')
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.then(response => {
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if (!response.ok) {
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throw new Error('Network response was not ok');
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}
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return response.json();
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})
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.then(data => console.log(data))
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.catch(error => console.error('Fetch error:', error));
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```
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**Tags**: [beginner](./level/beginner), [JavaScript](./theme/javascript), [Fetch API](./theme/fetch_api), [Error Handling](./theme/error_handling)
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Diff for: ‎level/intermediate/how_to_catch_errors_in_async_await.md

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## [How to catch errors in async/await](#how-to-catch-errors-in-async-await)
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### How to catch errors in async/await
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Wrap your async code in a try/catch block to handle errors gracefully.
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7+
```javascript
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async function fetchData() {
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try {
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const response = await fetch('https://api.example.com/data');
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const data = await response.json();
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console.log(data);
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} catch (error) {
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console.error('Error:', error);
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}
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}
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fetchData();
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```
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**Tags**: [intermediate](./level/intermediate), [JavaScript](./theme/javascript), [Async/Await](./theme/async_await), [Error Handling](./theme/error_handling)
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Diff for: ‎level/intermediate/how_to_catch_errors_in_callbacks.md

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## [How to catch errors in callbacks](#how-to-catch-errors-in-callbacks)
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### How to catch errors in callbacks
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When working with callbacks, ensure that errors are passed as the first argument to the callback function.
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7+
```javascript
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function performAsyncOperation(callback) {
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// Simulate error
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const error = new Error('Something went wrong');
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callback(error, null);
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}
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performAsyncOperation((error, result) => {
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if (error) {
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return console.error('Callback error:', error);
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}
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console.log(result);
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});
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```
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**Tags**: [intermediate](./level/intermediate), [JavaScript](./theme/javascript), [Callbacks](./theme/callbacks), [Error Handling](./theme/error_handling)
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