how to use database with javascript code example

Example 1: javascript read database

// Use https://github.com/JackChilds/jsmysqldb

// Then once it's setup you can just do this:

// Config that will be sent to server
const config = {
  "table" : "customers",
  "limit" : "50",
  "offset" : "0"
};

// Use the _POST_REQUEST function to send data to the server and get a response
_POST_REQUEST("link-to-server/database.php", 'config=' + JSON.stringify(config), (response) => {
  // Convert the response into an array of rows:
  var data = JSON.parse(response);
  // Now do what you want with data
  // data[row index][column name]
});

Example 2: local database with javascript

Your best option is:
https://pouchdb.com/

Example 3: local database with javascript

//get in GitHub
//more info in https://pouchdb.com
var db = new PouchDB('dbname');

db.put({
  _id: '[email protected]',
  name: 'David',
  age: 69
});

db.changes().on('change', function() {
  console.log('Ch-Ch-Changes');
});

db.replicate.to('http://example.com/mydb');