如何在javascript中一旦变量达到某个数字就对其进行更改

这应该有效，只需在玩家获得金钱（未经测试）时调用addMoney（）：

var copper = 0;
var silver = 0;
var gold = 0;
function addMoney(type, amount){
    if(type=='copper'){
        copper += amount;
        while(copper >= 100){
            copper -= 100;
            silver++;
        }
        while(silver >= 100){
            silver -= 100;
            gold++;
        }
    } else if(type=='silver'){
        silver += amount;
        while(silver >= 100){
            silver -= 100;
            gold++;
        }
    } else if(type=='gold'){
        gold += amount;
    } else {
        return false;
    }
    return true;
}

示例：

getMoney('silver', 5);

应返回true并增加白银5。

使用if语句：

if (copper == 100) {
 // set copper back to 0
 copper = 0;
}

我认为我们可以一次性处理所有类型的货币，并考虑到，当添加铜时，银或金可能超过100。

var Money = (function(){
    var m_copper = 9;
    var m_silver = 25;
    var m_gold = 30;                    //assume get from sever, may be ajax
    var targetTop = 100;
    var addCopper = function(){
        m_copper += amount.copper;
        while (m_copper >= targetTop){
            m_copper -= targetTop;
            m_silver += 1;
        }
    };
    var addSilver = function(){
        m_silver += amount.silver;
        while (m_silver >= targetTop){
            m_silver -= targetTop;
            m_gold += 1;
        }
    };
    var addGold = function(){
        m_gold += amount.gold;
    };
    var validate = function(){
        if (isNaN(amount.copper) || isNaN(amount.silver) || isNaN(amount.gold)){
            return false;
        }
        return true;
    }
    return {
        money: {
        copper: 0,
        silver: 0,
        gold: 0
        },              // actually this is not required, just for reference
        add: function( money ){
            amount = money;
            if (!(validate())){return;}
            addCopper();
            addSilver();
            addGold();
            return {copper: m_copper, silver: m_silver, gold: m_gold};
        }
    };
}());
var a = Money.add({copper: 103, silver: 245, gold: 10});
console.log(a);
var b = Money.add({copper: 103, silver: 245, gold: 10});
console.log(b);