How to Effectively Validate Decimal Numbers in JavaScript?

Validate Decimal Numbers in JavaScript: IsNumeric()

Problem Statement:

Determine the most effective and clear method for validating decimal numbers in JavaScript, ensuring cross-platform compatibility.

Test Cases:

• 1. IsNumeric('-1') → true
• 2. IsNumeric('-1.5') → true
• 3. IsNumeric('0') → true
• 4. IsNumeric('0.42') → true
• 5. IsNumeric('.42') → true
• 6. IsNumeric('99,999') → false
• 7. IsNumeric('0x89f') → false
• 8. IsNumeric('#abcdef') → false
• 9. IsNumeric('1.2.3') → false
• 10. IsNumeric('') → false
• 11. IsNumeric('blah') → false

Solution:

To achieve universal numeric validation, regardless of data type, a combination of isNaN and isFinite is recommended:

function isNumeric(n) {
    return !isNaN(parseFloat(n)) && isFinite(n);
}

This code effectively coerces any input into a number and checks for validity and finiteness. However, it's important to note that it will also consider hexadecimal and exponential formats as numeric.

Additional Approaches:

• jQuery's isNumeric: Compares the original input string with its floating-point representation to determine if they differ by less than 1.
• Angular 4.3 isNumeric: Subtracts the value from its floating-point representation and checks for a non-NaN result.

Considerations:

• Utilize Number.isNaN and Number.isFinite in ES6 for improved type conversion handling.
• The provided solution treats all numeric values as valid, including hexadecimal and exponential formats. Adjust the implementation based on specific validation requirements.

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