Node.js 定义和引用模块

定义一个Node模块：currency.js

var canadianDollar = 0.91;

function roundTwoDecimals(amount) {
    return Math.round(amount * 100) / 100;
}

exports.canadianToUS = function (canadian) {
    return roundTwoDecimals(canadian * canadianDollar);
}

exports.USToCanadian = function (us) {
    return roundTwoDecimals(us / canadianDollar);
}

引入一个模块：

下面的test-currency.js中的代码，它require了currency.js模块：

var currency = require('./currency');

console.log('50 Canadian dollars equals this amount of US dollars:');
console.log(currency.canadianToUS(50));

console.log('30 US dollars equals this amount of Canadian dollars:');
console.log(currency.USToCanadian(30));

输出结果：

50 Canadian dollars equals this amount of US dollars:
45.5
30 US dollars equals this amount of Canadian dollars:
32.97