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