A react component for image slideshow supporting slide, fade and zoom

A react component for image slideshow supporting slide, fade and zoom

A simple slideshow component built with react that supports slide, fade and zoom effects

React-Slideshow

A simple slideshow component built with react that supports slide, fade and zoom effects

Installation

npm install react-slideshow-image -S

yarn add react-slideshow-image

You can use three different effects of the slideshow. Check the demo

Slide Effect

source-js
import React from 'react';
import { Slide } from 'react-slideshow-image';

const slideImages = [
  'images/slide_2.jpg',
  'images/slide_3.jpg',
  'images/slide_4.jpg'
];

const properties = {
  duration: 5000,
  transitionDuration: 500,
  infinite: true,
  indicators: true,
  arrows: true,
  onChange: (oldIndex, newIndex) => {
    console.log(`slide transition from ${oldIndex} to ${newIndex}`);
  }
}

const Slideshow = () => {
    return (
      <div className="slide-container">
        <Slide {...properties}>
          <div className="each-slide">
            <div style={{'backgroundImage': `url(${slideImages[0]})`}}>
              <span>Slide 1</span>
            </div>
          </div>
          <div className="each-slide">
            <div style={{'backgroundImage': `url(${slideImages[1]})`}}>
              <span>Slide 2</span>
            </div>
          </div>
          <div className="each-slide">
            <div style={{'backgroundImage': `url(${slideImages[2]})`}}>
              <span>Slide 3</span>
            </div>
          </div>
        </Slide>
      </div>
    )
}

The default value for duration and transitionDuration is 5000 and 1000 milliseconds respectively

Fade Effect

source-js
import React from 'react';
import { Fade } from 'react-slideshow-image';

const fadeImages = [
  'images/slide_5.jpg',
  'images/slide_6.jpg',
  'images/slide_7.jpg'
];

const fadeProperties = {
  duration: 5000,
  transitionDuration: 500,
  infinite: false,
  indicators: true,
  onChange: (oldIndex, newIndex) => {
    console.log(`fade transition from ${oldIndex} to ${newIndex}`);
  }
}

const Slideshow = () => {
  return (
    <div className="slide-container">
      <Fade {...fadeProperties}>
        <div className="each-fade">
          <div className="image-container">
            <img src={fadeImages[0]} />
          </div>
          <h2>First Slide</h2>
        </div>
        <div className="each-fade">
          <div className="image-container">
            <img src={fadeImages[1]} />
          </div>
          <h2>Second Slide</h2>
        </div>
        <div className="each-fade">
          <div className="image-container">
            <img src={fadeImages[2]} />
          </div>
          <h2>Third Slide</h2>
        </div>
      </Fade>
    </div>
  )
}

The default value for duration and transitionDuration is 5000 and 1000 milliseconds respectively

Zoom Effect

source-js
import React from 'react';
import { Zoom } from 'react-slideshow-image';

const images = [
  'images/slide_2.jpg',
  'images/slide_3.jpg',
  'images/slide_4.jpg',
  'images/slide_5.jpg',
  'images/slide_6.jpg',
  'images/slide_7.jpg'
];

const zoomOutProperties = {
  duration: 5000,
  transitionDuration: 500,
  infinite: true,
  indicators: true,
  scale: 0.4,
  arrows: true
}

const Slideshow = () => {
    return (
      <div className="slide-container">
        <Zoom {...zoomOutProperties}>
          {
            images.map((each, index) => <img key={index} style={{width: "100%"}} src={each} />)
          }
        </Zoom>
      </div>
    )
}

CSS

This is what my css looks like. You can customize this to your own taste

.slide-container {
  width: 70%;
  margin: auto; }

h3 {
  text-align: center; }

.each-slide > div {
  display: flex;
  align-items: center;
  justify-content: center;
  background-size: cover;
  height: 300px;
}

.each-slide span {
  padding: 20px;
  font-size: 20px;
  background: #efefef;
  text-align: center;
}

.each-fade {
  display: flex;
}

.each-fade .image-container {
  width: 75%;
  overflow: hidden;
}

.each-fade .image-container img {
  width: 100%;
}

.each-fade h2 {
  width: 25%;
  display: flex;
  justify-content: center;
  align-items: center;
  margin: 0;
  background: #adceed;
}

Webpack configuration

If you bootstrapped the app without using create-react-app, you will need to add css loader and style loader to your webpack config

webpack.config.js

source-js
{
  module: {
    rules: [
      {
        test: /\.css$/,
        use: [
          { loader: "style-loader" },
          { loader: "css-loader" }
        ]
      }
    ]
  }
}

For those using Next.js , this should be your next.config.jsinorder to avoid errors relating to importing css files within node modules

next.config.js

source-js
const withCSS = require("@zeit/next-css");

if (typeof require !== "undefined") {
  require.extensions[".css"] = file => {};
}

module.exports = {
  webpack: config => {
    // Fixes npm packages that depend on `fs` module
    config.node = {
      fs: "empty"
    };

    return config;
  }
};

module.exports = withCSS();

HTML properties like className, data-* attributes and others will be applied to the parent div

Properties

Properties Type DefaultValue Description
duration integer 5000 Time it takes (milliseconds) before next transition starts
transitionDuration integer 1000 Determines how long the transition takes
defaultIndex integer 0 Specifies the first slide to display
infinite boolean true Specifies if the transition should loop throughout
indicators boolean false For specifying if there should be dots below the slideshow
scale number Required when using zoom to specify the scale the current slide should be zoomed to
arrows boolean true Determines if there should be a navigational arrow for going to the next or previous slide
autoplay boolean true Responsible for determining if the slideshow should start automatically
onChange function Callback that gets triggered at the end of every transition. The oldIndex and newIndex are passed as arguments

Methods

  1. goNext() It is used to programmatically transition the slide to the next one.

  2. goBack() If you want to show the previous slide, then use this function

  3. goTo(index) It can be used to transition the slide to a particular index. N.B Index starts from 0

To call the method you can use the slide's ref attribute and then call the method. this.slideRef.goNext()

Download Details:

GitHub: https://github.com/femioladeji/react-slideshow

Programming a Javascript Simon Game Tutorial

Programming a Javascript Simon Game Tutorial

In this javascript tutorial, I recorded myself live programming an html5 javascript simon game.

In this javascript tutorial, I recorded myself live programming an html5 javascript simon game.

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like this video if you found it useful and would like to see more videos of the same content.

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Understanding Memoization And Dynamic Programming in Javascript

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In this Javascript tutorial I will explain what memoization is, how to use it, when you should use memoization, how to use memoization, what dynamic programming is, how to use memoization in dynamic programming. Memoization is a big complicated word that you may have never even heard before, but you may be surprised to know that you are most likely already using memoization without even realizing it.

Memoization is a big complicated word that you may have never even heard before, but you may be surprised to know that you are most likely already using memoization without even realizing it. Memoization is just the act of caching values so that they can be calculated quicker in the future. Memoization is really useful in all parts of programming, but where it is most useful is in dynamic programming. In this video I will explain what memoization is, how to use it, and why it is so useful especially in dynamic programming.

🧠 Concepts Covered:

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  • How to use memoization in dynamic programming

Pagination in ReactJs

Pagination in ReactJs

There are a lot of resourceful materials online that give good insights into pagination in ReactJs, as well as NPM packages you can easily use

There are a lot of resourceful materials online that give good insights into pagination in ReactJs, as well as NPM packages you can easily use. As much as I appreciate those materials and love to use those packages, they mostly deal with loading the whole dataset on the page first then completely handle the pagination in the frontend. I am approaching this article with the concept of loading the exact data needed on the page, then manually loading other dataset based on the request when the user clicks the pagination number display. Below is the content structure to guide us through this article:

Table of Contents
  • Project Setup
  • HTML and CSS Styling
  • Pagination Data Format
  • Sample API request
  • Displaying the initial data
  • Showing Page Number and getting Other data
Project Setup

We are going to use create-react-app v0.1.0 which has the CSS Module configured already. Open your terminal and cd to the folder you want the project installed. Then run the below command:

npx create-react-app pagination  --use-npm

The above command will download the project into the folder calledpagination. You need to cd into the folder and run npm start. If everything goes well, you will have a page that looks like below:

HTML and CSS Styling

Open the project in your favorite code editor and locate the App.js file, We need to prepare our App.js to the look exactly like the way we want it by adding the HTML code and CSS style below:

Create a new file called App.module.css in the same directory where you have your App.js, then import it into your App.js using:

import styles from './App.module.css';

I want us to handle the display of the pagination number first, below is the style and HTML structure of what we are going to use.

  render() {
    

    return (
      <div className={styles.app}>
        
        <table className={styles.table}>
          <thead>
            <tr>
              <th>S/N</th>
              <th>First Name</th>
              <th>Last Name</th>
            </tr>
          </thead>
          <tbody>
              <tr>
                <td>1</td>
                <td>Abel</td>
                <td>Agoi</td>
              </tr>
              <tr>
                <td>2</td>
                <td>Muyiwa</td>
                <td>Aregbesola</td>
              </tr>
              <tr>
                <td>3</td>
                <td>Opeyemi</td>
                <td>Agoi</td>
              </tr>
              <tr>
                <td>4</td>
                <td>Ope</td>
                <td>Aina</td>
              </tr>
          </tbody>
        </table>


        <div className={styles.pagination}>
          <span>&laquo;</span>
          <span className={styles.active}>1</span>
          <span>2</span>
          <span>3</span>
          <span>4</span>
        </div>

      </div>
    );
  }

pagination_01.js

Add the content below into your App.module.css.

.app {
    width: 50%;
    margin: 0 auto;
}

table {
  border-collapse: collapse;
  border-spacing: 0; 
}


table {
  border-collapse: separate;
  border-spacing: 0;
  color: #4a4a4d;
  font: 14px/1.4 "Helvetica Neue", Helvetica, Arial, sans-serif;
  width: 100%;
}
tr {
  overflow-x: scroll;
}
th,
td {
  padding: 15px 15px;
  vertical-align: middle;
  /* text-align: left; */
}
thead {
  font-size: 14px;
  line-height: 24px;
  font-family: Lato;
  border: 1px solid transparent;

  max-width: 100%;
  font-weight: 900;
  line-height: 24px;
  mix-blend-mode: normal;

  color: rgba(51, 51, 51, .5);
  background: rgba(255, 255, 255, .9);
}
thead tr th {
  padding: 15px 15px;
  border: 1px solid transparent;


  text-align: left;
}
tbody {
  max-width: 100%;
}
tbody tr:nth-child(odd) {
  background: #f0f0f2;
}
tbody tr:hover {
  background: #f0f0f2;
}
td {
  padding: 15px 15px;
}
td:first-child {
}


.pagination {
    margin-top: 25px;
}
.pagination span {
  cursor: pointer;
  color: black;
  float: left;
  padding: 8px 16px;
  text-decoration: none;
  transition: background-color .3s;
  border: 1px solid #ddd;
}

.pagination span.active {
  background-color: #0099FF;
  color: white;
  border: 1px solid #0099FF;
}

pagination_app.module.css

Sorry for the plenty code written so far :), I want us to have a good looking table with pagination style in place before we move into the actual paging. If everything goes well, your view should look like below:

Pagination Data Format

In most cases, when you are making API calls to an endpoint that returns a paginated data, you need to pass at least the page number with the URL, hence a sample URL will look like below:

https://reqres.in/api/users?page=2

The most important thing to take note of in the URL above is the page=2 where 2 is the page number dataset we want to get. It can be 3,4 or any number as much as the dataset we have in the backend.

The response will always contain three important data which are per_page, total and the actual data we want to loop through. A sample response looks like below:

Sample API request

Talking about making an API request to the backend, We need a backend to make the request to, I decide to use https://reqres.in/ as the API endpoint for this tutorial because it is free, always available and reliable. You can decide to make your API request directly inside your component’s ComponentDidMount() or dispatch an action to redux from your ComponentDidMount() but for the purpose of this tutorial, we are going to make the API call from the App.js componentDidMount().

Firstly, we need to set the component’s state like below inside your App.js

  state = {
    users: null,
    total: null,
    per_page: null,
    current_page: null
  }

pagination_component_state.js

users is going to be the data we are going to loop over, while total and per_page is going to help us with calculating paging logic while the current_page will be used to style the active pagination link.

The next thing we should do is create a helper method that will serve the purpose of making an HTTP request to the API endpoint and also update the state with the response data. The method will look like below:

  makeHttpRequestWithPage = async pageNumber => {
    let response = await fetch(`https://reqres.in/api/users?page=${pageNumber}`, {
      method: 'GET',
      headers: {
        'Accept': 'application/json',
        'Content-Type': 'application/json',
      },
    });

    const data = await response.json();

    this.setState({
      users: data.data,
      total: data.total,
      per_page: data.per_page,
      current_page: data.page,
    });
  }

pagination_http_request.js

This method will accept a parameter called pageNumber so it can be reusable and will always update the state with the right data when the response is successful.

Since on page load, we need to make the HTTP request to the backend, and we are going to do this inside thecomponentDidMount() by calling the method above and passing it the first-page number we want which should be 1. Hence, the componentDidMount() will look like below:

 componentDidMount() {
    this.makeHttpRequestWithPage(1);
  }

pagination_componentDidMount.js

If we add console.dir(this.state.users) inside the render() method, below will be printed in the console

The null was before the data arrived, once the data arrived, it updates the state, hence the array of users data.

Displaying the initial data

Haven gotten the data needed, we need to loop through the data and display it. Hence we can update our render method to have below:

    let users;

    if (this.state.users !== null) {
      users = this.state.users.map(user => (
        <tr key={user.id}>
          <td>{user.id}</td>
          <td>{user.first_name}</td>
          <td>{user.last_name}</td>
        </tr>
      )); 
    }
    
    return (
      <div className={styles.app}>
        
        <table className={styles.table}>
          <thead>
            <tr>
              <th>S/N</th>
              <th>First Name</th>
              <th>Last Name</th>
            </tr>
          </thead>
          <tbody>
              { users }
          </tbody>
        </table>


        <div className={styles.pagination}>
          <span>&laquo;</span>
          <span className={styles.active}>1</span>
          <span>2</span>
          <span>3</span>
          <span>4</span>
          <span>&raquo;</span>
        </div>

      </div>
    );

gistfile1.txt

I replaced the dummy data we had inside the with the result of the loop which I equated to users. We have the assurance that when the state changes, ReactJs will automatically update the content of the table. The final stage is displaying the page logic and getting the other contents based on the page number clicked which will be sent to the API endpoint.

Showing Page Number and getting other data

Before we talk about showing page number automatically using the desired logic, I want us to manually show those numbers and make the actual API calls when the numbers are clicked. For now, we are going to hard code the pagination numbers ourselves like below:

<div className={styles.pagination}>
  <span onClick={() => this.makeHttpRequestWithPage(1)}>1</span>
  <span onClick={() => this.makeHttpRequestWithPage(2)}>2</span>
  <span onClick={() => this.makeHttpRequestWithPage(3)}>3</span>
  <span onClick={() => this.makeHttpRequestWithPage(4)}>4</span>
</div>

pagination_hard_code.js

The above code will look like below when previewed in the browser.

Notice that each span has an event handler attached to it, and I passed the page number to that event handler, so anytime we click on the pagination link, it will make a new HTTP request and update the component states, hence the user’s table data. We do not want to hard-code the links as we did above, so we need to automatically display those links.

So we’re planning on showing the page numbers for a series of pieces of data so that users can easily navigate multiple items. There are a few things that we need to know first:

  • The page that we’re on
  • Total number of items
  • Number of items per page

Good news is that we have captured all these things in our component’s state.

Next, we need to look at how we want to display the page numbers, there is a wide range of methods that people use:

  • Simple Next/Previous buttons with no numbers
  • A list of all possible pages
  • Page 1 & the last page, with the current page (and 2 above/below) shown

I personally prefer to show the very first page, that last page, and then the current page with 2 pages above & below. So for example on page 12 out of 24 pages we’d see:

1, 10, 11, 12, 13, 14, 24

This allows users to quickly navigate to the start, and to the end, as well as jump through multiple pages at once. For the purpose of this tutorial, I am going to show us how to show a list of all possible pages(item two above) then item three too.

The Arithmetic

We need to work out the total number of pages, for this, we want to take the total number of items that there are, and divide it by the number of items per page. But we want to make sure that we take that number and round it up.

So if there were 12 items in total, and we were showing 5 per page, we’d have a total of 3 pages of items. If we were to show 3 per page, we’d show 4 pages.

const pageNumbers = [];
for (let i = 1; i <= Math.ceil(this.state.meta.total / this.state.meta.per_page); i++) {
    pageNumbers.push(i);
}

page_logic_pagination.js

Haven gotten the page numbers, we need to loop through to display the span since we want to show all possible numbers first, our loop will look like below:

renderPageNumbers = pageNumbers.map(number => {
  let classes = this.state.current_page === number ? styles.active : '';

  return (
    <span key={number} className={classes} onClick={() => this.makeHttpRequestWithPage(number)}>{number}</span>
  );
});

pagination_all_numbers_loop.js

We need to update our pagination view to look like below:

<div className={styles.pagination}>
  <span onClick={() => this.makeHttpRequestWithPage(1)}>&laquo;</span>
  {renderPageNumbers}
</div>

pagination_view._01js

Congrats, we have successfully handle pagination, make HTTP request to the backend and changing the table content when user click on the page number to see.

To be sure we are on the same page, my App.js code looks like below:

import React, { Component } from 'react';
import styles from './App.module.css';

class App extends Component {


  state = {
    users: null,
    total: null,
    per_page: null,
    current_page: 1
  }


  componentDidMount() {
    this.makeHttpRequestWithPage(1);
  }


  makeHttpRequestWithPage = async pageNumber => {
    const response = await fetch(`https://reqres.in/api/users?page=${pageNumber}`, {
      method: 'GET',
      headers: {
        'Accept': 'application/json',
        'Content-Type': 'application/json',
      },
    });

    const data = await response.json();

    this.setState({
      users: data.data,
      total: data.total,
      per_page: data.per_page,
      current_page: data.page
    });
  }


  render() {

    let users, renderPageNumbers;

    if (this.state.users !== null) {
      users = this.state.users.map(user => (
        <tr key={user.id}>
          <td>{user.id}</td>
          <td>{user.first_name}</td>
          <td>{user.last_name}</td>
        </tr>
      ));
    }

    const pageNumbers = [];
    if (this.state.total !== null) {
      for (let i = 1; i <= Math.ceil(this.state.total / this.state.per_page); i++) {
        pageNumbers.push(i);
      }


      renderPageNumbers = pageNumbers.map(number => {
        let classes = this.state.current_page === number ? styles.active : '';

        return (
          <span key={number} className={classes} onClick={() => this.makeHttpRequestWithPage(number)}>{number}</span>
        );
      });
    }

    return (


      <div className={styles.app}>

        <table className={styles.table}>
          <thead>
            <tr>
              <th>S/N</th>
              <th>First Name</th>
              <th>Last Name</th>
            </tr>
          </thead>
          <tbody>
            {users}
          </tbody>
        </table>


        <div className={styles.pagination}>
          <span onClick={() => this.makeHttpRequestWithPage(1)}>&laquo;</span>
          {renderPageNumbers}
          <span onClick={() => this.makeHttpRequestWithPage(1)}>&raquo;</span>
        </div>

      </div>
    );
  }

}

export default App;

pagination_app.js

and my view like below:

We can change the page number display logic to below since it will accommodate for large dataset.

renderPageNumbers = pageNumbers.map(number => {
  let classes = this.state.current_page === number ? styles.active : '';

  if (number == 1 || number == this.state.total || (number >= this.state.current_page - 2 && number <= this.state.current_page + 2)) {
    return (
      <span key={number} className={classes} onClick={() => this.makeHttpRequestWithPage(number)}>{number}</span>
    );
  }
});

pagination_another_display_logic.js

Thanks for reading.