IdentifierBuilder - build the shortest possible unique names/keys. Helpful for compilers/minifiers/etc

IdentifierBuilder.js

/**
 * MIT Licensed (but really, do what you want with it)
 * 
 * 
 * Usage:
 * 
 * `IdentifierBuilder.create()` === `a`
 * `IdentifierBuilder.create()` === `b`
 * `IdentifierBuilder.create()` === `c`
 *  ...
 *  ...
 * `IdentifierBuilder.create()` === `aa`
 * `IdentifierBuilder.create()` === `ab`
 * `IdentifierBuilder.create()` === `ac`
 * 
 * You can use `.save()` and `.restore()` to
 * push/pop scopes.
 * 
 * `.createUniqueName(Number)` is used internally
 * but could be handy for others. Pass it a count
 * number and it will build a name assuming that
 * number of names have been built prior.
 * 
 * `IdentifierBuilder.createUniqueName(5000) === `gji`
 */
var IdentifierBuilder = (function () {

    var letters = "abcdefghijklmnopqrstuvwxyz".split(""),
        letterCount = letters.length,
        letterLastIndex = letterCount - 1;

    function createUniqueName(i) {
        if (i === undefined) return undefined;
        var name = "";
        var counter = -1;

        while (i > letterLastIndex) {
            i -= letterCount;
            counter++;
        }

        if (counter > -1) {
            name += createUniqueName(counter);
        }

        i = Math.floor(i);

        name += letters[i];

        return name;
    }

    var excludes = [];

    var IdentifierBuilder = {
        count: -1,
        stack: [],
        excludes: excludes,
        createUniqueName: createUniqueName,
        save: function () {
            this.stack.push(IdentifierBuilder.count);
            IdentifierBuilder.count = -1;
        },
        restore: function () {
            if (!this.stack.length) return;
            IdentifierBuilder.count = this.stack.pop();
        },
        create: function () {
            IdentifierBuilder.count++;
            var name = createUniqueName(IdentifierBuilder.count);

            if (excludes.indexOf(name) !== -1) {
                return this.create();
            } else {
                return name;
            }
        }
    };

    return IdentifierBuilder;

})();