peredur-palindrome/index.js

Palindrome detector

module.exports = Phrase;

// Adds 'reverse' to all strings.
String.prototype.reverse = function() {
  return Array.from(this).reverse().join("");
};

// Defines a Phrase object
function Phrase(content) {
  this.content = content;

  // Returns content processed for palindrome testing.
  this.processedContent = function processedContent() {
    return this.letters().toLowerCase();
  };

  // Returns the letters in the content
  // For example:
  //  new Phrase("Hello, world!").letters() === "Helloworld"
  this.letters = function letters() {
    return (this.content.match(/[a-z]/gi) || []).join("");
  };

  // Returns true for a palindrome, false otherwise
  this.palindrome = function palindrome() {
    if (this.processedContent()) {
      return this.processedContent() === this.processedContent().reverse();
    } else {
      return false;
    }
  };
}