Polynomial.js

/**
 * Polynomials are algebraic expressions consisting of two or more algebraic terms.
 * Terms of a polynomial are:
 * 1. Coefficients e.g. 5, 4 in 5x^0, 4x^3 respectively
 * 2. Variables e.g. y in 3y^2
 * 3. Exponents e.g. 5 in y^5
 *
 * Class Polynomial constructs the polynomial using Array as an argument.
 * The members of array are coefficients and their indexes as exponents.
 */
class Polynomial {
 constructor(array) {
 this.coefficientArray = array // array of coefficients
 this.polynomial = '' // in terms of x e.g. (2x) + (1)
 this.construct()
 }

 /**
 * Function to construct the polynomial in terms of x using the coefficientArray
 */
 construct() {
 this.polynomial = this.coefficientArray
 .map((coefficient, exponent) => {
 if (coefficient === 0) {
 return '0'
 }
 if (exponent === 0) {
 return `(${coefficient})`
 } else if (exponent === 1) {
 return `(${coefficient}x)`
 } else {
 return `(${coefficient}x^${exponent})`
 }
 })
 .filter((x) => x !== '0')
 .reverse()
 .join(' + ')
 }

 /**
 * Function to display polynomial in terms of x
 * @returns {String} of polynomial representation in terms of x
 */
 display() {
 return this.polynomial
 }

 /**
 * Function to calculate the value of the polynomial by substituting variable x
 * @param {Number} value
 */
 evaluate(value) {
 return this.coefficientArray.reduce((result, coefficient, exponent) => {
 return result + coefficient * Math.pow(value, exponent)
 }, 0)
 }
}

export { Polynomial }