Redux Document: English 中文

What is Redux

Redux is a predictable state container for JavaScript apps.

Redux also created by Facebook and it is a improvement from Flux. Redux is state management for any view library (mostly react)

When use Redux

Redux is design for complex UI, multiple view source or many interaction with server. If a simple UI, Redux is not necessary

Workflow

Example for Redux core

In index.html

How to connect your React app to a backend on the same origin

https://flaviocopes.com/how-to-serve-react-from-same-origin/

React Conditional Rendering

Original source: https://www.robinwieruch.de/conditional-rendering-react

Why We Switched to React Hooks

Original source: https://blog.bitsrc.io/why-we-switched-to-react-hooks-48798c42c7f

Why Can’t I Open My React App By Clicking Index.html?

From My Own Post

How To Use an IntersectionObserver in a React Hook

PDF archive: –>Link<–

Prototype

Foo.prototype.constructor === Foo; // true
f1.__proto__ === Foo.prototype; // true

f1.constructor === Foo; // true

f1 don’t have constructor, however depends on prototype chain engine will search f1.__proto__. This is line is equivalent to Foo.prototype.constructor === Foo

f1 instantiate a Foo:

Flex

Cheat Sheet provide by CSS-tricks.com

A Flexbox code Example

display

.container {
    display: flex;
}

flex-direction

.container {
    flex-direction: row | row-reverse | column | column-reverse;
}

flex-warp

.container {
    flex-wrap: nowrap | wrap | wrap-reverse;
}

flex-flow

This is a shorthand for the flex-direction and flex-wrap properties.

Create new post

hugo new posts/new.md

Add a picture

1. Basic markdown

   ![<alt name](< The route start from static folder>)

2. hugo build-in shortcut –> figure (src is start from static folder)

   \{\{< figure src="" title="" >}}

Add a reference link

Documentation of ref and relref

\[Neat](\{\{< ref "blog/neat.md" >}})
\[Who](\{\{< relref "about.md#who" >}})

Theme feature

This theme extended short code. See Theme Documentation - Extended Shortcodes

Reference: https://www.restapitutorial.com/httpstatuscodes.html

⭐︎ -> “Top 10” HTTP Status Code. More REST service-specific information is contained in the entry.

1XX Information

• 100 continue – Client should continue
• 101 switching protocols
• 102 processing (webDAV)

2XX Success

• ⭐︎200 OK – The request has succeeded.

  General status code. Most common code used to indicate success.

• ⭐︎201 Created – A new resource has been created and should return a URI.

  Successful creation occurred (via either POST or PUT). Set the Location header to contain a link to the newly-created resource (on POST). Response body content may or may not be present.

table

table
├── thead
│   └── tr
│       └── th
├── tbody
│   └── tr
│       └── td
└── tfoot
    └── tr
        └── td

Intersection Observer API

const option = {
    root: null,
    rootMargin: '0px',
    threshold: 0.7, // or an array [0.1, 0.2, ...]
};

const callback = (entries, observer) => {
    entries.forEach((entry) => {
        // Each entry describes an intersection change for one observed
        // target element:
        //   entry.boundingClientRect
        //   entry.intersectionRatio
        //   entry.intersectionRect
        //   entry.isIntersecting
        //   entry.rootBounds
        //   entry.target
        //   entry.time
    });
};
const observer = new IntersectionObserver(callBack, option);

observer.observer(nodeOne); //observing only nodeOne
observer.observer(nodeTwo); //observing both nodeOne and nodeTwo
observer.unobserve(nodeOne); //observing only nodeTwo
observer.disconnect(); //not observing any node

When node fulfilled observer option, callback function will run directly

Longest common subsequence

This is a typical recursive problem. The pseudocode is:

If S1[i] == S2[j], lcs(S1[i:],S2[j:]) = 1 + lcs(S1[i+1:],S2[j+1:])
else lcs(S1[i:],S2[j:]) = max(lcs(S1[i:],S2[j+1:]), lcs(S1[i+1s:],S2[j:]))

Recursive solution:

int longestCommonSubsequence(string text1, string text2) {
    if(text1.size() == 0 || text2.size() == 0 ){
        return 0;
    }

    if(text1[0] == text2[0]){
        return 1 + longestCommonSubsequence(text1.substr(1, text1.size()-1), text2.substr(1, text1.size()-1));
    }

    return max(longestCommonSubsequence(text1, text2.substr(1, text1.size()-1)),
            longestCommonSubsequence(text1.substr(1, text1.size()-1), text2));
}

Time complexity: O(2^n) Using dp could store the state that already calculate before.

What is dp problem

DP problem is a programming strategy which use extra space to save time. These problems need to store some state instead of calculate again. For most situation, DP is a strategy to reduce the time consuming for recursive problem.

1. Memorization
2. Tabulation

fibonacci example

The classic recursive problem:

const fib = (n) => {
    if (n <= 2) return 1;
    return fib(n - 1) + fib(n - 2);
};

How to memorize :

Download

Go to this link

workspace

Run go env in terminal. The variable GOPATH is the default workspace path. Project should under this folder.

In this workspace, file should structured as how you route your project:

.
├── bin
├── pkg
└── src
    └── <The home web page of version control>
        └── <User name>
            └── <Project name>

Example: