Angular Pipe to Singularize or pluralize word

singularize.pipe.ts

import { Pipe, PipeTransform } from '@angular/core';

@Pipe({
    name: 'singularize'
})

export class SingularizePipe implements PipeTransform {

    public transform(value: any, count: number = 1): string {
        return count > 1 ? plural(value) : singular(value);
    }

}

/**
 * Returns the singular of an English word.
 *
 * @export
 * @param {string} word
 * @param {number} [amount]
 * @returns {string}
 */
function singular(word: string, amount?: number): string {
    if (amount !== undefined && amount !== 1) {
        return word
    }
    const singular: { [key: string]: string } = {
        '(quiz)zes$': "$1",
        '(matr)ices$': "$1ix",
        '(vert|ind)ices$': "$1ex",
        '^(ox)en$': "$1",
        '(alias)es$': "$1",
        '(octop|vir)i$': "$1us",
        '(cris|ax|test)es$': "$1is",
        '(shoe)s$': "$1",
        '(o)es$': "$1",
        '(bus)es$': "$1",
        '([m|l])ice$': "$1ouse",
        '(x|ch|ss|sh)es$': "$1",
        '(m)ovies$': "$1ovie",
        '(s)eries$': "$1eries",
        '([^aeiouy]|qu)ies$': "$1y",
        '([lr])ves$': "$1f",
        '(tive)s$': "$1",
        '(hive)s$': "$1",
        '(li|wi|kni)ves$': "$1fe",
        '(shea|loa|lea|thie)ves$': "$1f",
        '(^analy)ses$': "$1sis",
        '((a)naly|(b)a|(d)iagno|(p)arenthe|(p)rogno|(s)ynop|(t)he)ses$': "$1$2sis",
        '([ti])a$': "$1um",
        '(n)ews$': "$1ews",
        '(h|bl)ouses$': "$1ouse",
        '(corpse)s$': "$1",
        '(us)es$': "$1",
        's$': ""
    }
    const irregular: { [key: string]: string } = {
        'move': 'moves',
        'foot': 'feet',
        'goose': 'geese',
        'sex': 'sexes',
        'child': 'children',
        'man': 'men',
        'tooth': 'teeth',
        'person': 'people'
    }
    const uncountable: string[] = [
        'sheep',
        'fish',
        'deer',
        'moose',
        'series',
        'species',
        'money',
        'rice',
        'information',
        'equipment',
        'bison',
        'cod',
        'offspring',
        'pike',
        'salmon',
        'shrimp',
        'swine',
        'trout',
        'aircraft',
        'hovercraft',
        'spacecraft',
        'sugar',
        'tuna',
        'you',
        'wood'
    ]
    // save some time in the case that singular and plural are the same
    if (uncountable.indexOf(word.toLowerCase()) >= 0) {
        return word
    }
    // check for irregular forms
    for (const w in irregular) {
        const pattern = new RegExp(`${ irregular[w] }$`, 'i')
        const replace = w
        if (pattern.test(word)) {
            return word.replace(pattern, replace)
        }
    }
    // check for matches using regular expressions
    for (const reg in singular) {
        const pattern = new RegExp(reg, 'i')
        if (pattern.test(word)) {
            return word.replace(pattern, singular[reg])
        }
    }
    return word
}

/**
 * Returns the plural of an English word.
 *
 * @export
 * @param {string} word
 * @param {number} [amount]
 * @returns {string}
 */
function plural(word: string, amount?: number): string {
    if (amount !== undefined && amount === 1) {
        return word
    }
    const plural: { [key: string]: string } = {
        '(quiz)$': "$1zes",
        '^(ox)$': "$1en",
        '([m|l])ouse$': "$1ice",
        '(matr|vert|ind)ix|ex$': "$1ices",
        '(x|ch|ss|sh)$': "$1es",
        '([^aeiouy]|qu)y$': "$1ies",
        '(hive)$': "$1s",
        '(?:([^f])fe|([lr])f)$': "$1$2ves",
        '(shea|lea|loa|thie)f$': "$1ves",
        'sis$': "ses",
        '([ti])um$': "$1a",
        '(tomat|potat|ech|her|vet)o$': "$1oes",
        '(bu)s$': "$1ses",
        '(alias)$': "$1es",
        '(octop)us$': "$1i",
        '(ax|test)is$': "$1es",
        '(us)$': "$1es",
        '([^s]+)$': "$1s"
    }
    const irregular: { [key: string]: string } = {
        'move': 'moves',
        'foot': 'feet',
        'goose': 'geese',
        'sex': 'sexes',
        'child': 'children',
        'man': 'men',
        'tooth': 'teeth',
        'person': 'people'
    }
    const uncountable: string[] = [
        'sheep',
        'fish',
        'deer',
        'moose',
        'series',
        'species',
        'money',
        'rice',
        'information',
        'equipment',
        'bison',
        'cod',
        'offspring',
        'pike',
        'salmon',
        'shrimp',
        'swine',
        'trout',
        'aircraft',
        'hovercraft',
        'spacecraft',
        'sugar',
        'tuna',
        'you',
        'wood'
    ]
    // save some time in the case that singular and plural are the same
    if (uncountable.indexOf(word.toLowerCase()) >= 0) {
        return word
    }
    // check for irregular forms
    for (const w in irregular) {
        const pattern = new RegExp(`${ w }$`, 'i')
        const replace = irregular[w]
        if (pattern.test(word)) {
            return word.replace(pattern, replace)
        }
    }
    // check for matches using regular expressions
    for (const reg in plural) {
        const pattern = new RegExp(reg, 'i')
        if (pattern.test(word)) {
            return word.replace(pattern, plural[reg])
        }
    }
    return word
}

Credit goes to
https://stackoverflow.com/a/57129703/10415423