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When coding in JavaScript, it is inevitable that you will encounter errors. However, understanding what these errors mean and how to troubleshoot them can be a challenge. In this article, we will discuss some of the most common JavaScript errors and how to debug them.

Syntax Errors

Syntax errors occur when the code you write is not written in valid JavaScript syntax. These errors usually show up as “syntax error” or “unexpected token” in the console.

For example, if you forget to close a bracket or parentheses, you will get a syntax error. To debug this kind of error, you can use a code editor to check for any typos or missing symbols.

Reference Errors

Reference errors occur when the code you wrote refers to a variable or function that does not exist. These errors usually show up as “ReferenceError” in the console. To debug this kind of error, you need to make sure that the variable or function you are referring to is properly defined.

Type Errors

Type errors occur when the code you wrote is trying to use a variable or function with an incorrect type. For example, if you are trying to use a string as a number, you will get a type error. These errors usually show up as “TypeError” in the console. To debug this kind of error, you need to make sure that the variable or function you are using is of the expected type.

Range Errors

Range errors occur when the code you wrote is trying to access a value that is outside of the expected range. For example, if you are trying to access an element in an array that is out of bounds, you will get a range error. These errors usually show up as “RangeError” in the console. To debug this kind of error, you need to make sure that the value you are trying to access is within the expected range.

URI Errors

URI errors occur when the code you wrote is trying to access a URI that is not valid. These errors usually show up as “URIError” in the console. To debug this kind of error, you need to make sure that the URI you are trying to access is correct.

Debugging

Debugging JavaScript errors can be a challenge, but with the right tools and techniques, it is possible to identify and fix them. By understanding the different types of errors and how to debug them, you can ensure that your JavaScript code is error-free.

Error handling

Javascript error handling is the process of responding to coding errors and other unexpected events in an application. Error handling is a critical component of developing robust and reliable applications. Generally, errors are handled by providing meaningful feedback to the user, logging the error, and/or attempting to gracefully recover from the error.

Error handling can be done in multiple ways. One way is to use the ‘try’ and ‘catch’ statements. With these statements, the code within the ‘try’ block is executed and if an error occurs, the code within the ‘catch’ block is executed. Another way is to use the ‘throw’ statement to throw an error and have it processed by the ‘catch’ block. Finally, there are also global error handlers that can be used to intercept and handle errors at a global level.

/*Javascript try/catch example*/

try {
    var x = y;
} catch (e) {
    console.log(e);
}

/*Javascript try/catch/finally example*/

try {
    var x = y;
} catch (e) {
    console.log(e);
} finally {
    console.log("Finally block executed!");
}

/*Javascript throw example*/

try {
    throw "myException"; // generates an exception
} catch (e) {
    console.log(e); // shows "myException"
}

/*Javascript throw example 2*/

try {
    throw new Error("Whoops!"); // generates an exception
} catch (e) {
    console.log(e.name + ": " + e.message); // shows "Error: Whoops!"
}

Error handling is important for providing meaningful feedback to the user, logging the error, and attempting to recover from the error. Without proper error handling, an application may crash and the user may be left without any indication of what went wrong. Proper error handling helps create a more reliable and user friendly application.