Simple and decoupled more or less game in Javascript

main.js

/**
 * Run + or - game.
 * 
 * To play it now, just call: runGame();
 * 
 * @param {Object} interface which you want to use. Default is Prompt
 * @param {Number} max number. Secret number will be between 0 and max. Default is 100
 * @param {boolean} decimal whether you allow decimal number. Default is false
 * @param {Number} secret number. Force the secret number. Default is random.
 */
function runGame(interface, max, decimal, secret) {
    if (!interface) {
        interface = Prompt;
    }
    
    if (!max) {
        max = 100;
    }
    
    if (!secret) {
        secret = Math.random() * max;
    }
    
    if (!decimal) {
        secret = Math.floor(secret);
    }
    
    interface.init(max, decimal);
    var user = max;
    var tries = 0;
    
    while (user != secret) {
        tries++;
        var clue = (user < secret) ? '+' : '-';
        user = interface.ask(user, clue);
    };
    
    interface.found(user, tries);
}

/**
 * Documentation interface. Do nothing.
 */
var Interface =
{
    /**
     * Called before running the game.
     * 
     * @param {Number} max number the game allows. The secret number is between 0 and max.
     * @param {boolean} decimal whether game allows decimal number.
     */
    init: function (max, decimal)
    {
    },
    
    /**
     * The game ask a number.
     * 
     * @param {Number} user the last number you said
     * @param {string} clue '+' or '-' if the secret is more or less than the last number you said
     * @returns {Number} the new number you say
     */
    ask: function (user, clue)
    {
        return 0;
    },
    
    /**
     * Called when you found the secret number
     * 
     * @param {Number} number the secret number you just found
     * @param {integer} tries number of tries used to find the number
     */
    found: function (number, tries)
    {
    }
};

/**
 * Prompt interface. Use default browser prompt and alert to play the game.
 */
var Prompt =
{
    init: function (max, decimal)
    {
        alert('You have to find '+(decimal ? 'a decimal number' : 'an integer')+' between zero and ' + max);
    },
    
    ask: function (user, clue)
    {
        return prompt(clue + ' than ' + user);
    },
    
    found: function (number, tries)
    {
        alert('Congratulations ! Number ' + number + ' found in ' + tries + ' tries.');
    }
};

/**
 * Bot interface. Will find the number automatically by using the middle number.
 */
var Bot =
{
    mem_min: 0,
    mem_max: 0,
    decimal: false,
    
    init: function (max, decimal)
    {
        console.log('I will find the secret '+(decimal ? 'decimal' : 'integer')+' between zero and '+max);
        
        Bot.mem_min = 0;
        Bot.mem_max = max;
        Bot.decimal = decimal;
    },
    
    ask: function (user, clue)
    {
        if (clue == '+') {
            Bot.mem_min = user;
        }
        
        if (clue == '-') {
            Bot.mem_max = user;
        }
        
        var botAnswer = (Bot.mem_min + Bot.mem_max) / 2;
        
        if (!Bot.decimal) {
            botAnswer = Math.floor(botAnswer);
        }
        
        console.log(clue + ' than '+user+', trying '+botAnswer);
        
        return botAnswer;
    },
    
    found: function (number, tries)
    {
        console.log('found '+number+' in '+tries+' times');
    }
};

/**
 * Risky bot, will try to find the number faster than Bot.
 */
var RiskyBot =
{
    mem_min: 0,
    mem_max: 0,
    decimal: false,
    
    init: function (max, decimal)
    {
        console.log('Yeaaaaah I will find the secret '+(decimal ? 'decimal' : 'integer')+' between zero and '+max);
        
        RiskyBot.mem_min = 0;
        RiskyBot.mem_max = max;
        RiskyBot.decimal = decimal;
    },
    
    ask: function (user, clue)
    {
        if (clue == '+') {
            RiskyBot.mem_min = user;
        }
        
        if (clue == '-') {
            RiskyBot.mem_max = user;
        }
        
        var botAnswer = (RiskyBot.mem_min + RiskyBot.mem_max) / 2;
        var riskValue = Math.floor((RiskyBot.mem_max - RiskyBot.mem_min) / 5);
        
        if (clue == '+') {
            botAnswer += riskValue;
        }
        
        if (clue == '-') {
            botAnswer -= riskValue;
        }
        
        if (!RiskyBot.decimal) {
            botAnswer = Math.floor(botAnswer);
        }
        
        console.log(clue + ' than '+user+', trying '+botAnswer);
        
        return botAnswer;
    },
    
    found: function (number, tries)
    {
        console.log('found '+number+' in '+tries+' times');
    }
};