找不到模块文件

Question

I am doing my Udemy course and I am stack now;( If anyone can help me it would be great: So the Error said "Error. Cannot find module '/Users/yui/Desktop/todolist-v1/date:js' Require stack. - /Users/yui/Desktop/todolist-v1/app.js"

but I am not sure why they cannot find module. Thanks in advance.

app.js file

//jshint esversion:6

const express = require("express");
const bodyParser = require("body-parser");
const date = require(__dirname + "/date.js");

const app = express();

let items = ["Buy Food","Cook Food","Eat Food"];
let workItems = [];

app.set("view engine", "ejs");

app.use(bodyParser.urlencoded({extended: true}));
app.use(express.static("public"));

app.get("/", function(req, res){

 let day = date();

 res.render("list", {ListTitle: day, NewListItems: items});

});

app.post("/", function(req, res){

 let item = req.body.newItem;

 if(req.body.list === "Work"){
   workItems.push(item);
   res.redirect("/work");
 }else{
   items.push(item);
   res.redirect("/")
 }
});

app.get("/about", function(req, res){
   res.render("about")
});

app.get("/work", function(req, res){
   res.render("list", {ListTitle: "Work List", NewListItems: workItems});
});

app.post("/work", function(req, res){
   let item = req.body.newItem;
   workItems.push(item);
   res.redirect("/work");
})


app.listen(3000, function(){
 console.log("Server is running on port 3000");
});

date.js file

//jshint esversion:6

module.exports = getDate;

function getDate(){

 let today = new Date();

 let currentDay = today.getDay();

 let day = "";
 　
 let options = {
    weekday: "long",
    day: "numeric",
    month: "long"
 };

 let day = today.toLocaleDateString("en-US", options);

};

Answer 1

If app.js and date.js in the same folder you didn't need to use __dirname.

Just use this line of code for import any js file.

const getDate = require('./date.js');

For example if this your project structure

/main_app_folder/app.js
/main_app_folder/helpers/data.js

You can use this line of code for import any js file inside helpers folder from app.js

const getDate = require('./helpers/date.js');

Answer 2

There is no use of using _dirname in const date = require(__dirname + "/date.js");Here is the explanation, why?
In Node.js, __dirname is always the directory in which the currently executing script resides. So if you typed __dirname into /dir1/dir2/myscript.js , the value would be /d1/d2 .

By contrast, . gives you the directory from which you ran the node command in your terminal window (ie your working directory) when you use libraries like path and fs . Technically, it starts out as your working directory but can be changed using process.chdir() .

The exception is when you use . with require() . The path inside require is always relative to the file containing the call to require .

For example...

Let's say your directory structure is

|--dir1
  |--dir2
     pathtest.js

and pathtest.js contains

var path = require("path");
console.log(". = %s", path.resolve("."));
console.log("__dirname = %s", path.resolve(__dirname));

and you do

cd /dir1/dir2
node pathtest.js

you get

. = /dir1/dir2
__dirname = /dir1/dir2

Your working directory is /dir1/dir2 so that's what . resolves to. Since pathtest.js is located in /dir1/dir2 that's what __dirname resolves to as well.

However, if you run the script from /dir1

cd /dir1
node dir2/pathtest.js

you get

. = /dir1
__dirname = /dir1/dir2

In that case, your working directory was /dir1 so that's what . resolved to, but __dirname still resolves to /dir1/dir2 .

Using . inside require ...

If inside dir2/pathtest.js you have a require call into include a file inside dir1 you would always do

require('../thefile')

because the path inside require is always relative to the file in which you are calling it. It has nothing to do with your working directory.