In this article. I will first explain some glossary from SQL then guide readers step by step on how to create a database, table, and add a record.

Tools

In this article, I will use SQLFiddle to create a table

What is SQL

Structured Query Language (SQL) can be classified into two parts

1. Data Definition Language (DDL): is responsible for defining database and table including field, data type, length etc.
2. Data Manipulation Language (DML): is responsible for adding, deleting, updating, looking up data. A more common way to say it is Create, Read, Update, Delete (CRUD)

As you can see…

In this article, I will explain how to use Javascript for Asynchronous programming.

Before we start, let’s first think about why we need Asynchronous programming. Asynchronous programming exists to solve the problem of blocking and save your time for waiting for the previous step to complete.

In the below example, considering each task takes 10 sec to complete. Synchronous will take around 30 sec to complete three tasks. On the other hand, asynchronous will only take a little more than 10 sec

Callback v.s. Promise v.s. Asyn/await

When you google javascript asynchronous, it might come up with the above glossaries…

In this article, I will explain why we need authentication and compare the difference between session-based authentication v.s. token-based authentication.

How Authentication works

To start with, let’s first think about how authentication works.

1. user login
2. username/password pass on to the server
3. server verified the information and grant the permission by sending back the authentication token
4. once we receive the authentication token, we will use it in every of our user request

HTTP stateless

You might be wondering why we need to show our authentication token in every client request. This is because HTTP is stateless, which means HTTP will not…

Have you ever seen the below code and wondering why people write something to wait for 0 sec?

setTimeout( () => {console.log('wait for 0 sec')},0)

It seems like a meaningless step as in real life you won't hold off someone and said wait for 0 seconds. However, this actually covers a very valuable theory that can transform your javascript code from single thread to multithread use.

I found a youtube clip that best explains event loop. In this article, I will share the note I took while watching this youtube clip: https://www.youtube.com/watch?v=8aGhZQkoFbQ.

Javascript = single thread

To answer this question…

In this article, I will explain object destructuring using pure Javascript and provide some examples of how I use it in my react project

How to use it with pure Javascript

1. basic extract

The basic use of destructuring is to us {} to extract one or more properties from your object. The below example shows that you can extract and create a string variable with the same property name.

Recently I am working on an app that required me to compare the DateTime data from API between my local pc time. Below I have listed out some useful method that I always use to help me compare and present the right time

Get local time

By default, when you are setting up a new Date Object, it will return a date object with your browser's time

After creating a Date object, you can use below method to get the data you need

Const and Let is a new feature introduced in ES6. This article will explain the difference and usage of const and let

Definition

First of all, let’s take a look at the definition in MDN

• Const : block-scoped, much like variables declared using the let keyword. The value of a constant can't be changed through reassignment, and it can't be redeclared.
• Let: statement declares a block-scoped local variable, optionally initializing it to a value.

By reading the definition, we can see that the main difference is on reassignment. In the next section, I will get into more detail on the…