JavaScript - Extra strength objects: Using Prototypes(extending built-in objects(String, palindrome method))

Head First JavaScript Programming
( O'Reilly Media)
Eric T. Freeman (著), Elisabeth Robson (著)

開発環境

• OS X Mavericks - Apple(OS)
• Safari, Firefox + Firebug, Google Chrome(Webプラウザ、プラグイン)
• BBEdit - Bare Bones Software, Inc. (GUI) , Emacs (CUI) (Text Editor)
• JavaScript (プログラミング言語)

Head First JavaScript Programming (Eric T. Freeman (著)、 Elisabeth Robson (著)、 O'Reilly Media )のChapter 13(Extra strength objects: Using Prototypes)、EXERCISE(p.611)を解いてみる。

EXERCISE(p.611)

コード(BBEdit, Emacs)

String.prototype.palindrome = function () {
    var i = 0,
        j = this.length - 1;
    
    while ( i <= j) {
        if (this[i] != this[j]) {
            return false;
        }
        i += 1;
        j -= 1;
    }
    return true;
};

print('abba'.palindrome());
print('abab'.palindrome());
print('abcba'.palindrome());
print('abcdba'.palindrome());