Module

When you remove a module manually or re import a database, some times you have a message like "The following module is missing from the file system...". this is due to deleted modules.

Note : On drupal the best practice is use drupal behaviors but not JS or Jquery codes such as:
<button onclick='myFunction()'>Click</button>

Drupal's event system allow to create triggers when an event has been happened like create a custom hook on drupal 7.

To get database table columns names of a mysql database you can use "DESCRIBE my_table;" method.

CAUTION : At this day (2017-10-12), Drupal commerce is very young. Therefor you can start the development of your e-commerce site but you may have bugs and security issues.

Example 1 (for drupal 7)

Step 1. Add file brows

Create a simple js file in your module directory (called yourModuleName.js) and enter the following Javascript.

Disable cache for a custom page from route declaration.

If you want to disable cache for a custom controller (Custom module), You have no_cache option (YOUR_MODULE.routing.yml).
Example :
File : mymodule.routing.yml

This is a simple example of a web service. For the example, We will make a service to multiply two numbers.

Create JSON WebService module

Create a module.

Here : mywebservice

Create a Drupal 8 module is a good idea, but develop as Drupal is BEST.

The famous tools PhpCS and PhpCBF allow you to check and correct (some) drupal coding standards and best practice errors.

To create a custom drush command, you must create a custom module like this (Here, mymodule).