JavaScript Function: Custom Error on a negative number

JavaScript Error Handling: Exercise-4 with Solution

Write a JavaScript function that takes a number as a parameter and throws a custom 'Error' if the number is negative.

Sample Solution:

JavaScript Code:

function validate_Positive_Number(n) {
  if (n < 0) {
    throw new Error('Error: Negative numbers are not allowed.');
  return n;


Sample Output:

"Error: Error: Negative numbers are not allowed.

Note: Executed on JS Bin


In the above exercise,

The "validatePositiveNumber()" function checks if a number "n" is less than zero using the comparison operator <. If it is, we throw a custom Error with the message 'Error: Negative numbers are not allowed.' This ensures that the function will not proceed with further operations if a negative number is passed.

If the number is not negative, the function returns the number itself.


Flowchart: Custom Error on a negative number.

Live Demo:

See the Pen javascript-error-handling-exercise-4 by w3resource (@w3resource) on CodePen.

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Error Handling Exercises Previous: Custom Error on the second number zero.
Error Handling Exercises Next: Custom Error on an empty array.

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