Error handling in JavaScript is essential for writing robust and reliable code. It involves catching, handling, and responding to errors or exceptions that may occur during the execution of your code. Here's an overview of error handling in JavaScript along with some examples:
Try...Catch Statement:
The
try...catchstatement is used to handle exceptions in JavaScript. Code that may throw an exception is placed inside thetryblock, and if an exception occurs, it's caught and handled in thecatchblock.try { // Code that may throw an exception throw new Error('Something went wrong!'); } catch (error) { // Handling the exception console.error(error.message); }
Throw Statement:
The throw statement is used to manually throw an exception. This can be useful for indicating errors or abnormal conditions in your code.
function divide(x, y) { if (y === 0) { throw new Error('Cannot divide by zero'); } return x / y; } try { divide(10, 0); } catch (error) { console.error(error.message); }
Error Types:
JavaScript provides built-in error types like Error, SyntaxError, TypeError, etc. You can also create custom error types by extending the Error object.
class CustomError extends Error { constructor(message) { super(message); this.name = 'CustomError'; } } try { throw new CustomError('Custom error message'); } catch (error) { console.error(error.name + ': ' + error.message); }
Finally Block:
The finally block is optional and is used to execute code after the try and catch blocks, regardless of whether an exception occurred or not.
try { // Code that may throw an exception } catch (error) { // Handling the exception } finally { // Cleanup code }
Global Error Handling:
You can also set up a global error handler using the window.onerror event to catch unhandled errors in your application.
window.onerror = function(message, source, lineno, colno, error) { console.error('An error occurred:', message); // Additional handling or logging };
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