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Table of contents
1.
Introduction 
2.
Popular Errors in JavaScript
2.1.
Undefined Methods/Functions
2.2.
Reference Errors
2.3.
Syntax Errors
2.4.
Type Error
2.5.
Logical Errors
3.
Error Handling in JavaScript
4.
Throw Statement in JavaScript
5.
How to Solve Errors in JavaScript?
6.
Frequently Asked Questions
6.1.
What is JavaScript?
6.2.
State popular errors in JavaScript?
6.3.
Use of try-catch block in JavaScript?
6.4.
What do you mean by a JavaScript throw statement?
6.5.
How do you handle errors in JavaScript?
7.
Conclusions
Last Updated: Mar 27, 2024
Medium

JavaScript Throw Statement

Author Sinki Kumari
0 upvote

Introduction 

JavaScript is a scripting language mainly used to create interactive web pages. It is not only limited to web pages but is also used in game development, web development, and many others. It is a dynamic programming language and is used on both the server side and the client side. Javascript is the most popular programming language among programmers.

JavaScript Throw Statement

In this blog, we will learn about JavaScript errors. We will see in-depth popular errors in JavaScript and how to resolve these errors. This blog will further cover Javascript throw statements and error handling in JavaScript.

Read More About, Basics of Javascript

Popular Errors in JavaScript

Errors in JavaScript are very common because of its dynamic nature. Errors can occur in JavaScript code due to programming errors, syntax errors, logical errors, and many other factors that lead to errors in the JavaScript code.  

Popular Errors in JavaScript

Various errors are resolved by using Javascript throw statements. Some of the popular errors are described below:

Undefined Methods/Functions

This is the most common error that mainly occurs by JavaScript programmers. Developers using JavaScript to build websites and gaming applications certainly find this error in their codes. The error occurs when you call a function/ method not present in the JS code. The compiler generates the error in the output console as the undefined method. 

Let's understand this through the example:

let child={
    name: "Ninja",
    age: 23,
    talk(){
        print(this.name);
    }
};
child.talkSoft();


Output

Output

The above code generates the error because the function talkSoft() is not defined in the JS code. 

Reference Errors

Reference errors in JavaScript are those errors that have been due to the programmer's logic. This error occurs when you try to access a variable that does not exist or has not been assigned or initialized in the code. This is the most common error in the JavaScript code.

Below is the code for a better understanding of this error:

var name = Coding;

 print(this.name)


Output

Output

Syntax Errors

This is the most popular error in JavaScript. This error occurs due to the programmer's code. The error is caused when you write a syntax other than the predefined syntax for the variable, function, return statement, break, etc. 

Syntax errors occur during the compile/parsing time, i.e., the reason this error is also called a parsing error.

Sound programming knowledge and correct syntax usage can easily resolve this error. 

let child={
    name: "Ninja",
    age: 23
    talk(){
        print(this.name);
    }
    
};


Output

Output

Type Error

Type errors are general errors in JavaScript. This error occurs when you try to operate on a value that is not possible for the compiler to perform. As we see in the below code, we are trying to change the number into an uppercase value. This is not possible as the number is not any alphabetical character.

var number = 123
number.toUpperCase()
print(number)


Output

Output

Logical Errors

The errors that have logical issues in the code. This error occurs because of an improper understanding of the problem and the solving logic behind those problems. Logical errors occur when the programmers try to accomplish a task that is not possible for the compiler to perform. 

The code does not have any syntax errors but has some logic issues.

Logical errors have different forms. They are difficult to track as they do not show any errors while running the code, but the code only works according to the desired output.

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Error Handling in JavaScript

Error handling is the most important part of the programming language. Because of so many errors in JavaScript, there is a need to handle those errors. JavaScript provides you with the feature to handle the runtime errors by using the try-catch, finally, block.

Error Handling

The try-catch block in JS is similar to other programming languages like C++ and Java. The try block performs some operation; if the operation or condition is not satisfied, then the catch block performs its operation. Finally, the block always runs irrespective of the try-catch block. It is independent of the other operation.  

try{
//operation
}
catch(Exception e){
//print statement to print the exception or error
//when operation in try is unsuccessful
}


Let's understand this through an example:  


try{
var class1 = ["simran", "sneha", "akshay", "aditya"];
print(class1);
print(class2);
}
catch(e){
   print (e) 
}


Output

Output

Finally block runs irrespective of the result from the try-catch block. The code in the finally block always run. 

try{
var class1 = ["simran", "sneha", "akshay", "aditya"];
print(class1);
print(class2);
}
catch(e){
   print (e) 
}
finally{
    print("I am finally");
}


Output

Output

Throw Statement in JavaScript

JavaScript gives you the ability to throw custom errors. Using JavaScript throw statements, you can define the exception in your code. You can throw any expression of the number, string, object, or even an object. 

JavaScript Throw Statement

You can throw any expression in the throw statement. It further helps the programmer detect code errors and generates a custom error. 

let age=12;
try{
var class1 = ["simran", "sneha", "akshay", "aditya"];
print(class1);
 if (age>=18){
     print("eligible to vote");
 }
 
else{
    throw  new Error ("age must be greater than 18");
} 
}
catch(e){
   print (e) 
}
finally{
    print("I am finally");
}


Output

Output

How to Solve Errors in JavaScript?

Don't worry about the errors in JavaScript. The errors in JavaScript can be solved by using try-catch blocks.

How to Solve Errors in JavaScript?

We can use the JavaScript throw statement that will help customize the code error further. 

Let’s see the code below for further understanding:

var class1 = ["simran", "sneha", "akshay", "aditya"];
print(class1);
print(b);

In the above code, we did not define b. This will further generate an error in the code and terminate our program. 


Output

Output

To resolve this problem, let us use the try-catch block statement so that our code runs successfully without any termination. 

try{
var class1 = ["simran", "sneha", "akshay", "aditya"];
print(class1);
print(b);
}
catch(e){
    print(e);
}
finally{
    print("I am finally");
}


Output

Output


Must Read Fibonacci Series in JavaScript

Frequently Asked Questions

What is JavaScript?

JavaScript is a scripting language mainly used to create interactive web pages. It is not only limited to web pages but is also used in game development, web development, and many other applications.

State popular errors in JavaScript?

There are various types of errors that occur in the JS code. Some of them are syntax errors, reference errors, type errors, URI errors, Range errors, etc.

Use of try-catch block in JavaScript?

Try-catch block is used to handle javascript errors. Using a try-catch block in JS code, you can handle the errors and exceptions in javascript and run the code successfully. This will save you from the runtime exceptions in JS.

What do you mean by a JavaScript throw statement?

Javascript throw statement helps you to customize errors in the code. It gives you the ability to throw custom errors. Using JavaScript throw statements, you can define the exception in your code. You can throw any expression of the number, string, object, or even an object. 

How do you handle errors in JavaScript?

To handle errors in JavaScript, programmers make use of try-catch statements. This helps the programmers to successfully execute the block and save the code from termination. The try-catch block is similar to other programming languages like C++ and Java. 

Conclusions

In this article, we learned about the JavaScript throw statement. We thoroughly discussed the errors in JavaScript, error handling, and finally, how we can handle those errors. 

To learn more about JavaScript, please refer to our blogs:

Regular Expressions in JavaScript

JavaScript multiline string 

JavaScript page load 

javascript selection and range 

Refer to our guided paths on Coding Ninjas Studio to learn more about DSA, Competitive Programming, JavaScript, System Design, etc. Enroll in our coursesrefer to the mock test and problems look at the interview experiences and interview bundle for placement preparations.

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