定义方法o1.js

const sum = function(a,b){
    return a+b;
}

const sub = function(a,b){
    return a-b;
}

module.exports={
    sum,
    sub
}

引用o2.js

const m  =require("./o1.js");

var result = m.sub(2,3)

console.log(result)

调用

node o2.js