JavaScript Throw Statement

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.

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

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

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. 

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

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.

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

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

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 courses, refer to the mock test and problems look at the interview experiences and interview bundle for placement preparations.

Happy Coding!