@wd006/js-function-library/src/math.js

A simple, modular, and reusable JavaScript function library providing common math, array, and utility functions.

/**
 * Adds two variables.
 *
 * @param {number} a - The first number to be added
 * @param {number} b - The second number to be added
 * @returns {number} - Sum of a and b
 *
 * @example
 * const number1 = 5;
 * const number2 = 7;
 * add(number1, number2);  // returns 12
 */
export function add(a, b) {
    return a + b;
}

/**
 * Subtracts two variables.
 *
 * @param {number} a - The first number to be subtracted
 * @param {number} b - The second number to be subtracted
 * @returns {number} - Difference of a and b
 *
 * @example
 * const number1 = 7;
 * const number2 = 5;
 * subtract(number1, number2);  // returns 2
 */
export function subtract(a, b) {
    return a - b;
}

/**
 * Multiplies two variables.
 *
 * @param {number} a - The first number to be multiplied
 * @param {number} b - The second number to be multiplied
 * @returns {number} - Product of a and b
 *
 * @example
 * const number1 = 7;
 * const number2 = 5;
 * multiply(number1, number2);  // returns 35
 */
export function multiply(a, b) {
    return a * b;
}

/**
 * Divides two variables.
 *
 * @param {number} a - The first number to be divided
 * @param {number} b - The second number to be divided (cannot be 0)
 * @returns {number} - Division of a by b
 *
 * @example
 * const number1 = 5;
 * const number2 = 2;
 * divide(number1, number2);  // returns 2.5
*/
export function divide(a, b) {
    if (b === 0) return null;
    return a / b;
}

/**
 * Calculates the factorial of a number.
 *
 * @param {number} x - Number to be calculated factorial
 * @returns {number} - Result of !x
 *
 * @example
 * const number = 5;
 * factorial(number);  // returns 120
*/
export function factorial(x) {
    let result = 1;
    for (let i = 1; x >= i; i++) {
        result *= i;
    }
    return result;
}
console.log(factorial(5));

/**
 * Checks if the number is an integer.
 *
 * @param {number} a - Number whose integer value is checked
 * @returns {boolean} - true or false
 *
 * @example
 * const number1 = 5.2;
 * const number2 = 2;
 * isInteger(number1);  // returns false
 * isInteger(number2);  // returns true
*/
export function isInteger(x) {
    return (x % 1 === 0);
}

/**
 * Checks if a number is even.
 * 
 * Non-integer numbers are first truncated to their integer part.
 *
 * @param {number} a - The number to check if it’s even.
 * @returns {boolean} - true or false
 *
 * @example
 * const number1 = 5.2;
 * const number2 = 2;
 * isEven(number1);  // returns false
 * isEven(number2);  // returns true
*/
export function isEven(x) {
    return (Math.trunc(x) % 2 === 0);

}

/**
 * Checks if a number is odd.
 * 
 * Non-integer numbers are first truncated to their integer part.
 *
 * @param {number} a - The number to check if it’s odd.
 * @returns {boolean} - true or false
 *
 * @example
 * const number1 = 5.2;
 * const number2 = 2;
 * isOdd(number1);  // returns true
 * isOdd(number2);  // returns false
*/
export function isOdd(x) {
    return (Math.trunc(x) % 2 !== 0);

}

/**
 * Generates a random integer in the specified range.
 * 
 * @param {number} min - Lower number limit.
 * @param {number} max - Higher number limit.
 * @returns {number} - Random number.
 *
 * @example
 * randomInt(3, 7);  // Possible returns: 3, 4, 5, 6, 7
*/
export function randomInt(min, max) {
    return Math.floor(Math.random() * (max - min + 1)) + min;
}

/**
 * Returns the average of a array of numbers.
 * 
 * @param {Array} array - Lower number limit.
 * @returns {number} - The average of array.
 *
 * @example
 * averageOfArray([1, 2, 3, 4, 5]);  // returns 3
*/
export function averageOfArray(array) {
    let total = 0, amount = 0;
    for (const num of array) {
        total += num;
        amount += 1;
    }
    return Number((total / amount));
}