node.js控制台-节点控制台中的“未定义”是什么？

Question

I'm novice in javascript. My knowlegde in scripting languages is python, and we know that it use modules for specific task. In any python console, we can use

import numpy as np

But it do not return anything in the console. So if i use the "same" thing in a node console i get this

var module = require('module')
undefined

So, i'm wondering what mean that undefined return from node console.

Answer 1

It's the return value from declaring a variable with var . Since it doesn't return anything, you get undefined . The assignment itself does however return the right-hand-side value, so chaining assignments is possible.

Answer 2

undefined表示表达式没有返回值。

Answer 3

Every command in node returns undefined unless you tell it to return something else. It won't affect anything your program, it is just the default return statement.