#Exception
- 1. Exception is an unwanted or unexpected problem, which occurs during the execution of a program.
- 2. If unexpected problem occurs at runtime , program execution will be disrupted.
- 3. Example: file input/output errors, or network communication errors.
#Exception handling
- 1. The process of handling unwanted or unexpected problem at runtime without affecting program execution is called as
Exception handling
. - 2. We can handle these exceptions using try, catch and finally.
#try , catch and finally
1. try
- 1. The try block contains the code that might throw an exception.
- 2. If an exception occurs within the try block, control is immediately transferred to the corresponding catch block.
2. catch
- 1. The catch block is used to handle exceptions that are thrown within the corresponding try block.
- 2. It contains code that will be executed if an exception is thrown, and is typically used to handle the exception in some way (e.g., logging an error message, displaying a user-friendly error message, or taking some other appropriate action).
3. finally
- 1. The finally block is used to specify code that should be executed regardless of whether or not an exception is thrown.
- 2. This block is typically used to clean up resources (e.g., closing files or closing network connections) that were allocated within the try block.
4. Example
- 1. 1try {2 // Code that might throw an exception34 const num = Number(prompt("Enter a number"));5 if (isNaN(num)) {6 throw new Error("Invalid number");7 }8 console.log("You entered the number " + num);9} catch (err) {10 // Code to handle the exception1112 console.error("An error occurred: "+err.message);13} finally {14 // Code to be executed regardless of whether an exception was thrown or not1516 console.log("Execution complete");17}
- 1.
#throw
- 1. throw is a keyword used to manually trigger an exception.
- 2. When throw is used, it causes the JavaScript interpreter to stop executing the current block of code and transfer control to the nearest catch block that can handle the exception.