Status

"Load web" : OK,
"GET,POST" : OK,
"DATABASE" : OK

About database, as we going to use SQL so which package should we choose? there are several such as

1. sqlite3 https://github.com/mapbox/node-sqlite3
2. PostgreSQL https://github.com/brianc/node-postgres
3. etc.

/* CLEAR */ Another maybe data structure? (<--- Important) Use sqlite3?.(Bank)

データベースについて、SQL採用するつもりなので、どっちのpackage選べばいいかな。。。
↑の通り。もう一つはデータの構造どうしましょう（大事）？

Database

This may help... DB Browser for SQLite
I will update db_helper later

LocalStorage (注)

After you clear the database, as this is not complete, I recommend to clear the localStorage through your browser.
Find someway to open up the console (i.e. Window Google Chrome F12 botton) then run

> localStorage.clear()
<<< undefined (response)

you are done!

Node.js

Please clone this and from this folder,

> npm install
> npm start

if any problem occur, please check whether node.js is installed
The packages which maybe useful to study right now are

    "express": "^4.15.4",
    "hbs": "~4.0.1",
    "body-parser": "~1.17.1"

For the longlist, please take a look at package.JSON.

How to

There is an easy way to build up this structure, using express generator
After you confirm the installation of node.js, run the following command

> npm install express-generator -g

then wait..........
Next, in my case, run

> express --view=hbs --hbs todolist

then follow the above commands.
REF:https://expressjs.com/en/starter/generator.html