JavaScript: Return the singular or plural form of the word based on the input number

JavaScript fundamental (ES6 Syntax): Exercise-164 with Solution

Singular or Plural Form

Write a JavaScript program that returns the singular or plural form of the word based on the input number.

If the first argument is an object, it will use a closure by returning a function that can auto-pluralize words that don't simply end in s if the supplied dictionary contains the word.

• Use a closure to define a function that pluralizes the given word based on the value of num.
• If num is either -1 or 1, return the singular form of the word.
• If num is any other number, return the plural form.
• Omit the third argument, plural, to use the default of the singular word + s, or supply a custom pluralized word when necessary.
• If the first argument is an object, return a function which can use the supplied dictionary to resolve the correct plural form of the word.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
// Define a function 'pluralize' to handle singular and plural forms of words
const pluralize = (val, word, plural = word + 's') => {
  // Define an inner function '_pluralize' to determine the correct plural form based on the count
  const _pluralize = (num, word, plural = word + 's') =>
    // Check if the number is 1 or -1, return singular form, otherwise return plural form
    [1, -1].includes(Number(num)) ? word : plural;
  // If 'val' is an object, return a function to handle pluralization based on the key-value pairs in the object
  if (typeof val === 'object') return (num, word) => _pluralize(num, word, val[word]);
  // Otherwise, directly use the inner function to determine the plural form
  return _pluralize(val, word, plural);
};

// Test the 'pluralize' function with different values and words
pluralize(0, 'apple'); // Output: 'apples'
pluralize(1, 'apple'); // Output: 'apple'
pluralize(2, 'apple'); // Output: 'apples'
pluralize(2, 'person', 'people'); // Output: 'people'

// Define a set of plural forms using an object
const PLURALS = {
  person: 'people',
  radius: 'radii'
};
// Create a specialized pluralize function based on the predefined plural forms
const autoPluralize = pluralize(PLURALS);
console.log(autoPluralize(2, 'person')); // Output: 'people'

Output:

people

Flowchart:

Live Demo:

See the Pen javascript-basic-exercise-163-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript program that returns the correct singular or plural form of a word based on a given count.
• Write a JavaScript function that appends "s" to a word if the count is not 1, handling irregular plural forms with a lookup.
• Write a JavaScript program that checks a number and returns a templated string with the appropriate word form.
• Write a JavaScript function that returns an object containing both singular and plural forms given a base word and count.

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