num-to-words/src/util.js

converts numbers into English words

/**
 * Checks if a certain number should be prefixed by a one.
 * i.e. "100" should be written as "one hundred" while
 *      "10" should not be written as "one ten".
 *
 * Examples:
 * _shouldPrefixWithOne(10); // returns False
 * _shouldPrefixWithOne(100); // returns True
 *
 * @param {number} n placeholder to check
 * @returns {boolean}
 */
export function shouldPrefixWithOne (n) {
  return n >= 100;
};

/**
 * Checks if a certain number should be joined with hyphens
 * e.g. "ninety-nine" versus "one hundred one"
 *
 * Examples:
 * _shouldHyphenate(10); // returns False
 * _shouldHyphenate(21); // returns True
 *
 * @param {number} n placeholder to check
 * @returns {boolean}
 */
export function shouldHyphenate (n) {
  return n >= 20 && n <= 99;
};