How to Handle Errors in JavaScript?
Last Updated :
12 Feb, 2025
In JavaScript Error Handling is used to find the errors in the code so, that the coder can find the particular issue to resolve it. Here are the different approaches to handle errors in JavaScript
1. Using try catch and finally statement
The try, catch, and finally blocks are used for error handling. The try block tests code, catch handles errors, and finally runs at the end no matter what the error was.
JavaScript
try {
const a = b
console.log(a)
}
catch (error) {
console.log('The error found here is', error)
}
finally {
console.log('runs each and every time')
}
Output
Handling using try catch and finally statement- In the above code the constant variable a is assigned a variable b which is not defined anywhere.
- In this case Reference error will be thrown as there is no memory allocated for the variable b which makes it difficult for JavaScript to refer the memory location of b
2. Explicitly causing errors using throw statement
The throw statement in JavaScript is used to explicitly throw error's in JavaScript and then these explicitly caused errors are caught by the catch block
JavaScript
try {
const a = 10;
{
if (a === 10) {
throw Error("Error is caused due to throw statement");
}
}
console.log(a);
} catch (error) {
console.log("The error found here is", error);
} finally {
console.log("runs each and every time");
}
Output
Explicitly causing errors using throw statement- In this code in the try block a error message 'Error is caused due to throw statement' is caused explicitly with the use of throw keyword
- In the catch part of this code the error is caught and is then printed on to the console
3. Errors using Error Object
The Error Object in JavaScript provides a complete object which contain's the message thrown by the code and the user can find out various aspect's from it like the error message, error name and error stack means at which part in the call stack the error is detected.
JavaScript
function A() {
B()
}
function B() {
C()
}
function C() {
throw new Error('Hello Error hai yahan pai')
}
try {
A()
}
catch (error) {
console.log(error.stack)
console.log(error.message)
console.log(error.name)
}
Output
Errors using Error Object- In the try block the function A is called which in turn calls function B which in turn calls the function C.
- The error is then caught by the catch block and then the error.message prints the error message from the error object.
- The error.stack prints the stack trace which means it will print the function in which the error is caused and will also print all the function's that had led to the call of that function.
4. Handling Asynchronous Errors with Promises
Handling asynchronous errors with Promises involves using .catch() to catch errors that occur during asynchronous operations, ensuring proper error handling in non-blocking code.
JavaScript
fetch('https://invalid.url')
.then(response => response.json())
.catch(error => {
console.error('Fetch failed:', error.message);
});
- The fetch method initiates an HTTP request.
- If the request fails (e.g., due to an invalid URL), the error is passed to the catch block.
- The catch block logs the error, ensuring graceful failure handling.
Handling Asynchronous Errors with Promises5. Handling Asynchronous Errors with async/await
The try...catch block is commonly used with async/await in asynchronous code to handle errors that may occur during the execution of asynchronous functions, allowing you to catch and manage exceptions in a clean and readable way.
JavaScript
async function f() {
try {
let response = await fetch('https://invalid.url');
let data = await response.json();
console.log(data);
} catch (error) {
console.error('Error fetching data:', error.message);
}
}
f();
- The await keyword pauses the function until the fetch promise resolves.
- If an error occurs (e.g., invalid URL), the catch block captures and logs it.
- This approach makes asynchronous code easier to read and manage.
Use cases of Error Management in JavaScript
- Network Requests: Handling errors in network operations (e.g., fetching data from an API) to manage issues like timeouts, unreachable servers, or invalid responses.
- User Input Validation: Catching errors when users enter invalid or unexpected data (e.g., text instead of numbers) to ensure smooth form submissions and data processing.
- File System Operations: Managing errors during file reading or writing (e.g., file not found, permission denied) to avoid crashes and ensure proper handling of file operations.
- Database Queries: Handling errors during database interactions (e.g., connection failures, query errors) to prevent system crashes and ensure proper logging and recovery.
- Asynchronous Operations: Using error handling in async/await or promises to catch errors in asynchronous tasks, ensuring that failures are handled properly without disrupting the main flow of the application.
Similar Reads
How To Handle Errors in React? Handling errors in React is essential for creating a smooth user experience and ensuring the stability of your application. Whether you're working with functional or class components, React provides different mechanisms to handle errors effectively. 1. Using Error BoundariesError boundaries are a fe
5 min read
JavaScript - How to Handle Errors in Promise.all? To handle errors in Promise.all(), you need to understand that it fails immediately if any of the promises reject, discarding all resolved values. This behavior can lead to incomplete operations and potential application crashes. The best way to manage errors in Promise.all() is by using .catch() in
3 min read
How to Handle Errors in Node.js ? Node.js is a JavaScript extension used for server-side scripting. Error handling is a mandatory step in application development. A Node.js developer may work with both synchronous and asynchronous functions simultaneously. Handling errors in asynchronous functions is important because their behavior
4 min read
How to Handle Syntax Errors in Node.js ? If there is a syntax error while working with Node.js it occurs when the code you have written violates the rules of the programming language you are using. In the case of Node.js, a syntax error might occur if you have mistyped a keyword, or if you have forgotten to close a parenthesis or curly bra
4 min read
How to create custom errors in JavaScript ? In this article, we will learn to create custom errors with some examples. Errors represent the state of being wrong in condition. Javascript handles a predefined set of errors by itself but if you want to create your own error handling mechanism you can do that with custom errors functionality avai
2 min read
How to handle an undefined key in JavaScript ? In this article, we will try to analyze how we may handle an undefined key (or a property of an object) in JavaScript using certain techniques or approaches (via some coding examples). Firstly let us quickly analyze how we may create an object with certain keys along with their values using the foll
3 min read
How to debug JavaScript File ? Debugging is essential because there are many errors that are not giving any kind of messages so to find out that we debug the code and find out the missing point. Example 1: Â Using console.log() Method In this, we can find out the error by consoling the code in various places. Using a console is on
2 min read
How to Catch JSON Parse Error in JavaScript ? JSON (JavaScript Object Notation) is a popular data interchange format used extensively in web development for transmitting data between a server and a client. When working with JSON data in JavaScript, it's common to parse JSON strings into JavaScript objects using the JSON.parse() method. However,
1 min read
How to escape try/catch hell in JavaScript ? In this article, we will try to understand how we may escape from multiple try/catch hell (that is multiple sequences of occurrences of try/catch blocks) in JavaScript. Let us first quickly visualize how we may create a try/catch block in JavaScript using the following illustrated syntax: Syntax: Fo
4 min read
How to handle exceptions in PHP ? Exceptions in PHP: The exception is the one that describes the error or unexpected behavior of the PHP script. The exception is thrown in many PHP tasks and classes. User-defined tasks and classes can also do differently. The exception is a good way to stop work when it comes to data that it can use
2 min read