I was using Ajax to do some DOM manipulation in a Rails app I was working on. None of what I was doing needed to involve a round trip to server, the only reason I hit the server at all was to take advantage of Rails' (well, ActiveSupport's) pluralize function. Also, this technique required an extra action that I decided to eliminate as I try to move to a more RESTful architecture.

The only part of ActiveSupport's Inflector class I implemented are the ones I needed. I implemented even fewer of Rails' Inflector-based functions.

Stick all this in a file, such as "inflector.js".

/*
 * This script depends on no outside libraries.
 */

Inflector = {
    /*
     * The order of all these lists has been reversed from the way 
     * ActiveSupport had them to keep the correct priority.
     */
    Inflections: {
        plural: [
            [/(quiz)$/i,               "$1zes"  ],
            [/^(ox)$/i,                "$1en"   ],
            [/([m|l])ouse$/i,          "$1ice"  ],
            [/(matr|vert|ind)ix|ex$/i, "$1ices" ],
            [/(x|ch|ss|sh)$/i,         "$1es"   ],
            [/([^aeiouy]|qu)y$/i,      "$1ies"  ],
            [/(hive)$/i,               "$1s"    ],
            [/(?:([^f])fe|([lr])f)$/i, "$1$2ves"],
            [/sis$/i,                  "ses"    ],
            [/([ti])um$/i,             "$1a"    ],
            [/(buffal|tomat)o$/i,      "$1oes"  ],
            [/(bu)s$/i,                "$1ses"  ],
            [/(alias|status)$/i,       "$1es"   ],
            [/(octop|vir)us$/i,        "$1i"    ],
            [/(ax|test)is$/i,          "$1es"   ],
            [/s$/i,                    "s"      ],
            [/$/,                      "s"      ]
        ],
        singular: [
            [/(quiz)zes$/i,                                                    "$1"     ],
            [/(matr)ices$/i,                                                   "$1ix"   ],
            [/(vert|ind)ices$/i,                                               "$1ex"   ],
            [/^(ox)en/i,                                                       "$1"     ],
            [/(alias|status)es$/i,                                             "$1"     ],
            [/(octop|vir)i$/i,                                                 "$1us"   ],
            [/(cris|ax|test)es$/i,                                             "$1is"   ],
            [/(shoe)s$/i,                                                      "$1"     ],
            [/(o)es$/i,                                                        "$1"     ],
            [/(bus)es$/i,                                                      "$1"     ],
            [/([m|l])ice$/i,                                                   "$1ouse" ],
            [/(x|ch|ss|sh)es$/i,                                               "$1"     ],
            [/(m)ovies$/i,                                                     "$1ovie" ],
            [/(s)eries$/i,                                                     "$1eries"],
            [/([^aeiouy]|qu)ies$/i,                                            "$1y"    ],
            [/([lr])ves$/i,                                                    "$1f"    ],
            [/(tive)s$/i,                                                      "$1"     ],
            [/(hive)s$/i,                                                      "$1"     ],
            [/([^f])ves$/i,                                                    "$1fe"   ],
            [/(^analy)ses$/i,                                                  "$1sis"  ],
            [/((a)naly|(b)a|(d)iagno|(p)arenthe|(p)rogno|(s)ynop|(t)he)ses$/i, "$1$2sis"],
            [/([ti])a$/i,                                                      "$1um"   ],
            [/(n)ews$/i,                                                       "$1ews"  ],
            [/s$/i,                                                            ""       ]
        ],
        irregular: [
            ['move',   'moves'   ],
            ['sex',    'sexes'   ],
            ['child',  'children'],
            ['man',    'men'     ],
            ['person', 'people'  ]
        ],
        uncountable: [
            "sheep",
            "fish",
            "series",
            "species",
            "money",
            "rice",
            "information",
            "equipment"
        ]
    },
    ordinalize: function(number) {
        if (11 <= parseInt(number) % 100 && parseInt(number) % 100 <= 13) {
            return number + "th";
        } else {
            switch (parseInt(number) % 10) {
                case  1: return number + "st";
                case  2: return number + "nd";
                case  3: return number + "rd";
                default: return number + "th";
            }
        }
    },
    pluralize: function(word) {
        for (var i = 0; i < Inflector.Inflections.uncountable.length; i++) {
            var uncountable = Inflector.Inflections.uncountable[i];
            if (word.toLowerCase == uncountable) {
                return uncountable;
            }
        }
        for (var i = 0; i < Inflector.Inflections.irregular.length; i++) {
            var singular = Inflector.Inflections.irregular[i][0];
            var plural   = Inflector.Inflections.irregular[i][1];
            if ((word.toLowerCase == singular) || (word == plural)) {
                return plural;
            }
        }
        for (var i = 0; i < Inflector.Inflections.plural.length; i++) {
            var regex          = Inflector.Inflections.plural[i][0];
            var replace_string = Inflector.Inflections.plural[i][1];
            if (regex.test(word)) {
                return word.replace(regex, replace_string);
            }
        }
    }
}

function ordinalize(number) {
    return Inflector.ordinalize(number);
}

/*
 * Javascript doesn't have optional parameters or overloading so I had to use
 * the ever popular pseudo options hash object technique.
 * required properties:
 *     count    Number of objects to pluralize
 *     singular Singular noun for the objects
 * optional property:
 *     plural   Plural (probably irregular) noun for the objects
 * examples:
 *      pluralize({ count: total_count, singular: "Issue" })
 *      pluralize({ count: total_count, singular: "Goose", plural: "Geese" })
 */
function pluralize(options) {
    return options.count + " " + (1 == parseInt(options.count) ?
        options.singular :
        options.plural || Inflector.pluralize(options.singular));
}