3.commonjs模块

1.首先建一个math.js

exports.add = function(a, b){
	return a + b;
}
exports.sub = function(a, b){
	return a - b;
}
exports.mul = function(a, b){
	return a * b;
}

2.然后建一个app.js 引人math.js

var math = require('./math');
console.log(math);//{ add: [Function], sub: [Function], mul: [Function] }
var command = process.argv[2];
var a = Number(process.argv[3]);
var b = Number([process.argv[4]]);
var value = math[command](a, b);
console.log(value);//node app.js mul 1 2 结果为2

CMD运行

node app.js add 1 2 //3
node app.js sub 1 2 //-1
node app.js mul 1 2 //2