In this article, we will be talking about handle exceptions in JavaScript. We will be managing some errors that are being faced. Here, this handle exception is the process for converting the message of the code errors into an error message-friendly code. This step is an important one.
In this article, we will be covering the following basics of exception handling.
- What is meant by the handle exception
- Types of errors in JavaScript
- The ways through which the exception can be handled within the JavaScript
- What is meant by exception handling is the features that handle the errors and try to maintain the flow of the code.
This exception explains why errors have occurred when it occurs within the codes. It also explains that at which point the error has occurred. For example, most of the developers or such input errors are making some kind of typing mistake of the errors within the code happen when the developers or such input errors are making some kind of typing mistake.
Some of the basic reasons that why the exception errors occur:
- Whenever we try to divide any of the numbers by 0. This leads to infinity, and in results, the exceptions are shown.
- When we try to call any files that don’t exist within our system.
- When the input provided by the user is wrong.
- When we have a bad network connection.
If the program developer someone cannot manage the failure within the code or the program, then it will be useless for him to make it a successful one. However, like the whole code is correct, the entire code becomes useless due to a silly mistake.
Here in this kind of situation, the handling of the exceptions plays a vital role. Whenever any type of error occurs and an exception is said to occur. Then there is a code to handle the exception produced by the translator of the JavaScript. Here the exception can get changed but not the errors.
The types of JavaScript errors could be different when we try to execute the code within the JavaScript environment. There are three errors types, namely:
- Syntax Errors
- Runtime errors
- Logical errors
Table of Contents
Syntax errors
These are such kinds of mistakes that the system is mostly unpredictable. This stops the programs from running, or the code doesn’t work. Within the platform of JavaScript, these errors could be due to:
errors of the Spelling
when some characters are missing at the end of the statement.
The indentation is being misused.
Runtime Errors
Such errors occur at the time of running the code. These errors are only identified when we run the code within the platform. When such kind of errors occurs, it leads to the exception. So such kinds of errors are being then handled by the handlers of the exception.
Such errors occur when:
the data which the program is trying to call is not present in the system.
Therefore, the data that we are using is an invalid type.
Logical Errors
These errors don’t lead to any kind of exception. These are the ones in which the programmers don’t get the intended results. These are the type of errors that are not identified quickly. These can only be determined by the testing known as the thorough test.
The objects within the errors
Whenever such errors arise, this leads to an error in the execution. This stops the code from running and shows an object of the error.
The object error has two types of properties:
name: It gives the error name.
Message: the message for the error is returned to the form of the message.
JavaScript uses the six most familiar objects for the errors, known as the error foundation.
- EvalError
- RangeError
- ReferenceError
- Syntax Error
- TypeError
- URIError
Handling of the exception in JavaScript
Now, as we have some idea about the exception, we will be looking at the methods to stop them from crashing our code.
These exceptions are handled in the try-catch-finally statements and throw statements within the JavaScript.
The Key terms
This statement, known as the try-catch-finally, is a code responsible for handling the exceptions.
Here the try is a clause that runs the program that in return generates the exception.
We will be Inserting the code of the JavaScript inside the script tagging for understanding the working of the exception handling.
Let’s have a look at an example:
Code
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript try catch</h2>
<p>Please input a number:</p>
<input id="demo" type="text">
<button type="button" onclick="myFunction()">Test Input</button>
<p id="p01"></p>
<script>
function myFunction() {
const message = document.getElementById("p01");
message.innerHTML = "";
let x = document.getElementById("demo").value;
try {
if(x == "") throw "empty";
if(isNaN(x)) throw "not a number";
x = Number(x);
if(x < 10) throw "The value is less than 10";
if(x > 10) throw "The value is greater than 10";
}
catch(err) {
message.innerHTML = "Input is " + err;
}
}
</script>
</body>
</html>
Output
Conclusion
In this article, we have discussed the handle exceptions in JavaScript, its different types, and the object errors in JavaScript. We have discussed the other names of the errors that take place. Here, we have also learned the different techniques used for handling the exceptions within JavaScript.
