Dice Rolling

dice.js

//What die to roll {die}, which is 20 for a d20, 8 for a d8, etc.
//A modifier to add to the total, if any.
//Returns an object with the individual results in an array, and the total.
var roll = function(num, die, mod){
    var results = [];
    var total = 0;
    if (num > 0){
        for(var i = 0; i < num; i++){
            var result = Math.floor((Math.random() * die) + 1);
            results.push(result);
            total += result;
        }
    }
    total += mod;
    var obj = {
        total: total,
        results: results,
        num: num,
        die: die,
        mod: mod
    };

    return obj;
};

//Dice interpreter function
//Takes a string of dice to roll
//Eg:  "2d6+1d4+8"
//And then does each roll and totals the results.

var roll_dice = function(die_str){
    var die_str = die_str.replace(/- */,'+ -');
    var die_str = die_str.replace(/D/,'d');
    var re = / *\+ */;
    var items = die_str.split(re);
    var total = 0;
    var result_str = "";
    for(var i in items){
        var str = items[i];
        if(str.indexOf("d") > -1){
            //this is a die roll
            var parts = str.split("d");
            var num = parseInt(parts[0]);
            var die = parseInt(parts[1]);
            var res = roll(num, die, 0);
            total += res.total;
            if(result_str === ""){
                result_str += "[" + res.results + "]";
            } else {
                result_str += " + " + "[" + res.results + "]";
            }
        } else {
            //this is a mod to add
            var mod = parseInt(str);
            total += mod;
            if(result_str === ""){
                result_str += str;
            } else {
                result_str += " + " + str;
            }
        }
    }
    console.log(total);
    console.log(result_str);
    var obj = {
        total: total,
        result: result_str,
        orig: die_str
    };
    return obj;
}