JavaScript Errors
JavaScript Errors
In JavaScript, errors can occur during the execution of code when something unexpected happens. These errors can be divided into two categories: syntax errors and runtime errors.
- Syntax errors: Syntax errors occur when there is a problem with the syntax of your code, such as a missing parenthesis, curly brace, or semicolon. Syntax errors prevent your code from running at all.
For example, the following code will generate a syntax error because the opening curly brace is missing:
function myFunction() {
console.log("Hello, world!");
- Runtime errors: Runtime errors occur when your code is syntactically correct but there is an error in the logic of your code. Runtime errors cause your code to stop executing at the point where the error occurred.
For example, the following code will generate a runtime error because the variable x is not defined:
function myFunction() {
console.log(x);
}
myFunction(); // Uncaught ReferenceError: x is not defined
JavaScript provides a built-in Error object that can be used to handle errors in your code. You can create a new Error object using the throw statement:
throw new Error("Something went wrong!");
You can also create custom error objects that inherit from the Error object using the class syntax:
class MyError extends Error {
constructor(message) {
super(message);
this.name = "MyError";
}
}
throw new MyError("Something went wrong!");
To handle errors in your code, you can use the try…catch statement:
try {
// code that may throw an error
} catch (error) {
// code to handle the error
}
The catch block is executed if an error is thrown in the try block. The error parameter contains information about the error, such as the error message and stack trace.
In addition to the try…catch statement, you can also use the finally block to execute code after the try block, regardless of whether an error was thrown or not:
try {
// code that may throw an error
} catch (error) {
// code to handle the error
} finally {
// code to execute regardless of whether an error was thrown or not
}