All Validators

Browse copy-paste ready snippets for your projects.

414 Snippets

Is Adult (18+)

datetime

Checks if the provided date of birth makes the user at least 18 years old.

#dob#age#restriction

const isAdult = (birthDate: Date): boolean => {
  const today = new Date();
  const age = today.getFullYear() - birthDate.getFullYear();
  const m = today.getMonth() - birthDate.getMonth();
  return age > 18 || (age === 18 && m >= 0 && today.getDate() >= birthDate.getDate());
};

Is Business Day

datetime

Checks if date is Mon-Fri.

#workday#weekday

const isBusinessDay = (date: Date): boolean => {
  const day = date.getDay();
  return day !== 0 && day !== 6;
};

Is Weekend

datetime

Checks if date is Saturday or Sunday.

#weekend#holiday

const isWeekend = (date: Date): boolean => date.getDay() === 0 || date.getDay() === 6;

Is Leap Year

datetime

Determines if a year is a leap year.

#calendar#year

const isLeapYear = (year: number): boolean => (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0;

Days Between Dates

datetime

Calculates number of days between two dates.

#diff#duration

const daysBetween = (d1: Date, d2: Date): number => {
  const oneDay = 24 * 60 * 60 * 1000;
  return Math.round(Math.abs((d1.getTime() - d2.getTime()) / oneDay));
};

Is Future Date

datetime

Checks if a date is strictly in the future.

#validation#time

const isFuture = (date: Date): boolean => date.getTime() > Date.now();

Is Valid Date Object

datetime

Checks if a Date object is valid and not "Invalid Date".

#check#error-handling

const isValidDate = (d: any): boolean => d instanceof Date && !isNaN(d.getTime());

Is Past Date

datetime

Checks if a date is in the past.

#validation#time

const isPast = (date: Date): boolean => date.getTime() < Date.now();

Is Same Day

datetime

Checks if two dates are on the same day.

#comparison#calendar

const isSameDay = (d1: Date, d2: Date): boolean => d1.toDateString() === d2.toDateString();

Is Prime Number

math

Efficiently checks if a number is prime.

#algorithm#number

const isPrime = (n: number): boolean => {
  if (n <= 1) return false;
  if (n <= 3) return true;
  if (n % 2 === 0 || n % 3 === 0) return false;
  for (let i = 5; i * i <= n; i += 6) {
    if (n % i === 0 || n % (i + 2) === 0) return false;
  }
  return true;
};

Is Even

math

Checks if a number is even.

#basic#number

const isEven = (n: number): boolean => n % 2 === 0;

Is Odd

math

Checks if a number is odd.

#basic#number

const isOdd = (n: number): boolean => n % 2 !== 0;

Is Power of Two

math

Bitwise check if number is a power of 2.

#bitwise#binary#optimization

const isPowerOfTwo = (n: number): boolean => n > 0 && (n & (n - 1)) === 0;

GCD (Greatest Common Divisor)

math

Euclidean algorithm for GCD.

#algorithm#math

const gcd = (a: number, b: number): number => (!b ? a : gcd(b, a % b));

Clamp Number

math

Restricts a number within a min and max range.

#utility#bounds

const clamp = (num: number, min: number, max: number): number => Math.min(Math.max(num, min), max);

Random Integer In Range

math

Generates a random integer between min and max (inclusive).

#random#rng

const randomInt = (min: number, max: number): number => Math.floor(Math.random() * (max - min + 1)) + min;

Factorial

math

Calculates n! (recursive).

#algorithm#recursive

const factorial = (n: number): number => (n <= 1 ? 1 : n * factorial(n - 1));

Fibonacci

math

Returns nth Fibonacci number.

#algorithm#sequence

const fib = (n: number): number => n <= 1 ? n : fib(n - 1) + fib(n - 2);

Is Positive

math

Checks if number is positive.

#basic#number

const isPositive = (n: number): boolean => n > 0;

Is Negative

math

Checks if number is negative.

#basic#number

const isNegative = (n: number): boolean => n < 0;

Is Integer

math

Checks if number is an integer.

#type#number

const isInteger = (n: number): boolean => Number.isInteger(n);

Is Float

math

Checks if number has decimal places.

#type#number

const isFloat = (n: number): boolean => !Number.isInteger(n) && !isNaN(n);

Luhn Algorithm (Credit Card)

finance

Validates credit card numbers using checksum.

#payment#algorithm#validation

const luhnCheck = (num: string): boolean => {
  let arr = (num + '').split('').reverse().map(x => parseInt(x));
  let lastDigit = arr.splice(0, 1)[0];
  let sum = arr.reduce((acc, val, i) => (i % 2 !== 0 ? acc + val : acc + ((val * 2) % 9) || 9), 0);
  return (sum + lastDigit) % 10 === 0;
};

Format Currency

finance

Formats number as currency with locale.

#format#money

const formatCurrency = (amount: number, locale = 'en-US', currency = 'USD'): string => 
  new Intl.NumberFormat(locale, { style: 'currency', currency }).format(amount);

What is CodeSnippets?

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Every code snippet in our library is carefully crafted, tested, and optimized for real-world use cases. From simple email validation to complex credit card verification using the Luhn algorithm, from date calculations to XSS sanitization—we cover the validation patterns you encounter daily as a developer.

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