Throw statements are used in combination with Try-Catch staements to define an user defined exceptions. When an error is caught during execution of a try block, the throw statement is executed and program flow goes to catch statements as needed.

NOTE: The code after the throw statement is not executed. If there is no catch block defined, the program terminates immediately.

Syntax for Throw statement

throw expression;


  • expression – It is expression which gets thrown when error occurs.

While throwing an exception an object can be referenced too. That can be a JavaScript error object such as RangeError,  EvalError, SyntaxError … etc or an user defined object. A throw exception can also be re-thrown, until an exception handler is found or more debugging information is found. 

Example of user-defined error object throwing error message

Example with multiple throw statements and JavaScript error objects


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