Basic knowledge

1. HTML CSS is not a programming language

   • JavaScript is a programming language (browser programming language). Web pages written in HTML CSS do not have any functionality. All functions have to be done through JavaScript.

   • Java brand backend language, the best language for writing backend. It is cooperative web development, big data, enterprise-level applications, big data, and Android development.

   • C embedded, operating system, driver development

   • C++ games and the like, desktop software

   • C# software development

     
     

2. How to use JS

   Add <script></script> tags to the body to use JS. Usually coding JS before the closing tag of the body. This is because JS loads slowly and the HTML & CSS loads quickly. From the user’s point of view, the overall web page should be swiped first.

   
   

3. JS core

   • ECMAScript Core

   • DOM page manipulation

   • BOM browser related operations

   
   

4. Comments in JS

   // Single line

   /* Multiple lines */

   
   

5. Variable

   A variable is a space in memory dedicated to storing data.

   How to use variable:

   1. Variables should be declared by var.

   2. The variable should be named var box.

   3. The variable should be assigned var box = 1.

   4. Semicolon in JS ; can be added or not (preferably)

      
      

6. Console

   Console is for debugging JS, it is useless after the project development is over. The console can prompt errors. Console is in the browser -> right click -> inspect -> Console.

   Console.log() function is console output (in JS).

   
   

7. Project deployment

   The project can be accessed locally on the computer. Logically, other people can also access it through IP address + path + file name, but it’s practically not feasible because of firewall.
   To actually deploy project, you need to run the project to the server. The server is a high-performance computer that runs 24 hours a day without shutting down. Generally, small projects only rent a small part of the space in the server.

   
   

   Domain name: like www.google.com, and bind it’s IP address. When the domain name is entered, it is resolved by DNS (domain name system) and resolved into an IP address in the service and accessed.

   URL address: like https://www.google.com/src/index. protocol://domain name: port number + path (file path or route).

   Protocol http, https (secure mode), FTD (file upload), file.
   Port number: Different applications, different functions of the server. Such as 80 web pages, 3306 databases. Can be omitted by default.

   Path: The file path or the route set by the frontend/backend.