How to Create a Validator That Accepts Only Specific Numeric Values

How can I create a validator that accepts only specific numeric values in my application?

function validateNumber(input) { const validNumbers = [1, 2, 3, 4, 5]; return validNumbers.includes(input); }

Creating a validator to restrict input to specific numeric values is essential for ensuring data integrity in applications. This guide outlines how to implement such a validator in JavaScript.

function validateNumber(input) { const validNumbers = [1, 2, 3, 4, 5]; // Check if the input is a number and exists in validNumbers return typeof input === 'number' && validNumbers.includes(input); } // Example usage console.log(validateNumber(3)); // true console.log(validateNumber(6)); // false

Causes

• Using incorrect syntax in the validation function.
• Not defining the array of accepted numbers properly.
• Misunderstanding input types (e.g., strings vs. numbers).

Solutions

• Define an array of valid numbers clearly.
• Utilize the `includes()` method to check if the input exists in the array.
• Convert input types as necessary before validation.

Mistake: Forgetting to check the input type before validation.

Solution: Ensure you check the type of input (e.g., if it’s a number) before testing its inclusion in the array.

Mistake: Defining the valid values incorrectly or using invalid data types.

Solution: Always check that the values in your array are correctly defined and of the correct type.

Mistake: Using a loose equality check instead of strict.

Solution: Use strict equality (===) to avoid type coercion issues.