 Courses from Ryan Harris

React is one of the web’s most popular frameworks for building JavaScript applications. 

If you know what you’re doing, React can drastically simplify how you build, use, and maintain code.

Whether you’re a React newbie or you’re ready for advanced techniques, you can level-up with egghead. Explore our in-depth courses, lessons, and community resources to build more powerful applications and crack open your career.

react

Let’s display a user’s NFT ticket in our dApp. 

Using Axios, we can make a call to OpenSea’s API, passing in the user’s address and the smart contract address as params.

Display a User's NFTs Using the OpenSea API

Ethereum is a decentralized, open-source blockchain with smart contract functionality. 

ethereum

We want to update the “Checked In” property on our NFT tickets once a user checks in with our dApp. 

To accomplish this we create `checkIn` method in our smart contract. To write `checkIn` we can just copy and paste a large portion of our `mint` method and remove the call to `safeMint`, set the id to the user’s token, set Checked In to `true`, and replace the placeholder image with our IPFS image.

Update an NFT’s Image and Other Metadata

A placeholder image isn’t going to cut it for our awesome NFT tickets. 

We can upload our own images to IPFS at [https://www.pinata.cloud/](https://www.pinata.cloud/)

Upload Static Assets to IPFS with Pinata

To confirm ownership we first have to add a `confirmOwnership` method to our smart contract and redeploy it. 

Then, we can call that `confirmOwnership` method on the connected smart contract within a `useEffect` hook in our React dApp.

Confirm a Wallet Owns an NFT in a Smart Contract

With the `QrReader` component from `react-qr-scanner` library, scanning a user’s wallet QR code is straightforward. 

We first make sure that the QR reader can be open and closed in the UI. Then using the `onScan` prop on `QrReader`, we get the wallet address from the QR code and add it to local state.

Scan an Ethereum Wallet's QR Code

Time to set up our dApp to actually mint an NFT when the buy button is clicked. 

`.mint` is called on our `connectedContract` with an object containing a `value` property. The value property is the NFTs cost in gwei. 

Then to polish everything up, we’ll add a loading state, and link the user to the transaction on Etherscan using `useToast`

Mint an NFT from a React dApp

It’s helpful for users to know how many NFTs are currently available and how many there are total.  

This information can be found on the smart contract. In our dApp we can get it off our `connectedContract`, stored locally in React state, using the `totalTicketCount` and `availableTicketCount` methods.

Fetch Mint Info From a Smart Contract

We need to give the owner of the smart contract the ability to open and close an NFT sale in the React dApp UI. 

We’ll use the `.openSale` and `.closeSale` methods off of the `connectedContract` stored in React state. Then for the best possible experience we’ll create a pending state while the sale is opening or closing. During the pending state the buttons will be disabled. 

Then we’ll bring in `useToast` from chakra-ui to give a message depending on if the opening/closing of the sale was successful or not.

Open and Close an NFT Sale From a React dApp

We don’t want any user to be able to access admin pages. Let’s check if the user’s wallet address matches the address of our connected smart contract. 

This can be done by using OpenZeppelin to get the owner address from the smart contract, then comparing that to the currently connected address.

Fetch the Owner's Wallet Address From a Smart Contract

Now it’s time to connect your dApp to your smart contract on the Rinkeby test network. 

You will copy over the `nfTixBooth.json` file from the smart contract project. Then, using the `ethers` library, you’ll connect to the smart contract.

Connect a React dApp to a Smart Contract Using ethers.js

Since we are storing the user’s wallet address in React state, it is lost when the dApp is reloaded. To fix this, we’ll cache the address in localStorage. 

We’ll use the `useEffect` hook to look for an address in localStorage if there isn’t one in local state.

Cache a MetaMask Wallet Address in localStorage

Users should also be given the option to disconnect their wallet from your dApp.

There isn’t a programatic way to accomplish this, but we can remove their wallet address from state, adjust the UI, and use `react-router` to navigate them to root in order to provide a clear UX.

Disconnect MetaMask from a React dApp

We need a way for our user’s MetaMask wallets to connect to our dApp. We can accomplish this with the `ethereum` object that MetaMask injects into the browser’s `window`. 

When the user connects we’ll save their wallet address as state using the `useState` hook.

Support MetaMask Connections to a React dApp

Let’s create a dApp that connect to a smart contract on the Rinkeby test network! 

I’ve created a starter repo ****for you. Just run `git clone git@github.com:ryancharris/nftix-demo-ui.git`. Then just run `yarn` and add the smart contract’s address to an ENV file.

Set Up a React dApp From a Starter

So far we’ve been deploying to a blockchain running locally. Let’s get our smart contract onto the Rinkeby test network. 

Create an account on the command line and then get some ether through a faucet. In this lesson, we used [https://faucets.chain.link/rinkeby](https://faucets.chain.link/rinkeby) to get our fake ether. Then we use our same deploy script, except with the `--network` flag that we set to `rinkeby`.

Deploy a Smart Contract to the Rinkeby Testnet

Right now our sale can be open and closed by anyone. We want to take ownership of our smart contract to prevent this.

We'll use `Ownable` from OpenZeppelin, Set the `openSale` and `closeSale` public functions to `onlyOwner`, and then set the owner of the smart contract in the deploy script.

Restrict Smart Contract Functions to a Specified Owner

We want to actually sell our NFT tickets, so let’s set a mint price. 

In our smart contract, we can just set the price to an integer variable. We’ll then make our mint function `payable`. When a function is payable in Solidity it means it can receive ether. 

Once our mint function is payable, we can call the `require` function to check if the initiator of the function is sending enough ether.

Set a Mint Price on Your NFT Smart Contract

Let’s add an image to our SVG. We’ll start by creating a base 64 encoded SVG using `Base64` and `OpenZeppelin`. 

Then, in order to actually associate an image to our token, we’ll have to apply it to our token’s metadata. We’ll create a base64 JSON object that includes our image, save it as a string variable that lives in memory, then call the `_setTokenURI` method with our NFT’s ID and our metadata string.

Add an Image to an NFT with Token Metadata

We need our users to be able to mint their NFT tickets. We also need to limit the number of available tickets. 

Start by making sure each NFT has a unique ID. OpenZeppelin gives us the handy utility `Counters` for this. We will increment the ID each time an NFT is minted. 

Once your NFTs have IDs you can use the inherited `_safeMint` function from OpenZeppelin in your `mint` function to mint an NFT for the initiator of the function. Also, make sure to increment the ID and decrement the number of remaining NFTs.

Add a Mint Function to Your NFT Smart Contract

ERC-721 is the Non-Fungible Token (NFT) standard that implements an API for tokens inside of Smart Contracts. 

Luckily, the OpenZeppelin library makes it easy to enforce this standard with the `ERC721URIStorage` class! We just import the `ERC721URIStorage` class and specify that our contract is an instance of it. Then, set the return type in our constructor to `ERC721`.

Create an ERC-721 Token with OpenZeppelin

Simply deploy your smart contracts with the scaffold by running `yarn deploy`.  Once deployed your can view your contract in the UI. 

But, the default smart contract that comes with scaffold-eth isn’t useful for our NFT ticketing app. So, we’ll edit the contract to have a `saleIsActive` state and write a couple of functions that update the state to `true` or `false`

Deploy a Smart Contract to Localhost with scaffold-eth

When comparing two visually similar websites, it can often be challenging to precisely identify the subtle differences between them. To facilitate a rapid analysis of these discrepancies, a practical technique involves leveraging Chrome's integrated developer tools to capture full-page screenshots of each site. Subsequently, these screenshots can be uploaded to a platform like AI Studio. There, the AI can analyze the images and generate a report detailing the variations. This entire process, leveraging a few quick shortcuts, can be completed in under a minute, delivering a comprehensive breakdown of the differences for efficient comparison and analysis.

Quickly Compare Two Sites Using AI Studio with Chrome Full Page Screenshots

It's fairly trivial to create a React project, but there's always a big hurdle between creating it locally and making it shareable so that someone else can run it. This lesson walks you through the process of automating creating a React project locally, creating the repository where it's going to be hosted, and creating shareable links where it can be run so that you can quickly and easily create single one-off demos and shoot them over to your friends and coworkers for sharing your code ideas in a working environment.


```bash
share-react-project() {
  if [[ -z "$1" ]]; then
    echo "Usage: share-react-project <project_name>"
    return 1
  fi

  local project_name="$1"
  local github_username=$(gh api /user --jq '.login')

  echo "Creating Vite project: $project_name"
  pnpm create vite "$project_name" --template react

  cd "$project_name"

  echo "Initializing Git repository"
  git init

  echo "Adding all files to Git"
  git add .

  echo "Creating initial commit"
  git commit -m "Initial commit"

  local codesandbox_link="https://codesandbox.io/p/github/${github_username}/${project_name}"

  echo "Adding CodeSandbox link to README.md"
  echo "" >> README.md
  echo "## CodeSandbox" >> README.md
  echo "[![Open in CodeSandbox](https://assets.codesandbox.io/github/button-edit-blue.svg)](${codesandbox_link})" >> README.md

  echo "Adding README.md to Git"
  git add README.md

  echo "Committing README.md changes"
  git commit -m "Add CodeSandbox link"

  echo "Creating GitHub repository: $github_username/$project_name"
  gh repo create "$github_username/$project_name" --public

  echo "Pushing to remote 'origin'"
  git push -u origin main

  echo "Project '$project_name' created successfully!"
  echo "GitHub repository: https://github.com/$github_username/$project_name"
  echo "CodeSandbox link: $codesandbox_link"
}
```

Automate Creating a Local React Project, GitHub Repository, and Live Hosted Demo in a Single Command

[Verdaccio](https://verdaccio.org/) is a fully featured NPM registry that you can run locally on your machine. It’s a great tool for testing your release process, running end-to-end tests, and simulating real-world scenarios like deploying packages, installing them, and verifying functionality as an end user would.

Nx includes a [generator](https://nx.dev/features/generate-code) that simplifies setting up Verdaccio. To configure it, run:

```shell
npx nx g @nx/js:setup-verdaccio   
```

This command installs the necessary NPM packages and creates a `project.json` file with a `local-registry` target. To start the local registry, open a new terminal window and run:

```shell
npx nx local-registry
```

This will:
- Launch the Verdaccio registry.
- Configure NPM to point to the local Verdaccio server at `http://localhost:4873`.

> **Note:** A `project.json` file provides an advanced way to define scripts, offering more flexibility than a traditional `package.json` for managing complex targets.

Setup local Verdaccio server to release NPM packages

Learn how to spin up a local NPM registry powered by Verdaccio to test deploy your NPM packages.

In TypeScript, developers often begin by defining the structure of their data using type definitions or interfaces, which is a powerful way to ensure type safety. However, as applications grow and become more complex, simply defining the shape of an object might not be enough to guarantee its consistent creation and behavior throughout the codebase. This often leads to situations where objects that are intended to be of a certain "type" might be missing crucial properties or have incorrect data, which can be difficult to track down and debug.

This lesson tackles the question of when and why to move beyond basic type definitions and embrace classes in TypeScript. It demonstrates how classes provide a more robust mechanism for defining object structure, enforcing type constraints, and ensuring consistent object creation. By establishing a clear blueprint for objects, classes not only improve compile-time type safety but also offer runtime benefits and better code organization, ultimately helping developers avoid common pitfalls associated with loosely structured objects in larger TypeScript projects.

Stop Avoiding Classes in TypeScript

Karabiner isn't only for your keyboard. It can also hijack your mouse buttons and enable them to be similar to layers on your keyboard, where holding down a mouse button can allow you to tap keys on your keyboard to trigger commands and macros that can completely revolutionize your workflows. For example, you can hold down the right mouse button and tap on R to go to references in VS Code. Or hold down the right mouse button and tap the left mouse button to chop up videos and Screenflow.

This completely unlocks a whole new world of possibilities and use cases for your mouse as you can hover your mouse over anywhere on the page. And just tapping keys on your keyboard allows you to trigger mouse actions, to trigger keyboard actions, or to trigger macros and applications and terminal commands. and anything that your imagination can come up with. 

Karabiner: Rethinking Right-Click as a Macro Command Center

Make an HTML table more readable on mobile devices by using the ::before pseudo-element. We add labels to each cell, so they appear like cards when the table is viewed on smaller screens. The ::before content is set using a data-label attribute for each cell to enhance mobile viewability without horizontal scrolling.



Create a mobile friendly table with the before pseudo-element

Learn to use CSS ::before pseudo-element for mobile-friendly HTML tables. Add labels to cells for enhanced readability on mobile, avoiding horizontal scroll.

Any app of a decent size has event flows and messages being passed around. At a certain point it becomes complicated to explain it through prose and you want to turn towards diagrams. Now setting aside the time to create diagrams that accurately describe what's happening in your codebase can be quite time consuming. Luckily, with today's AI tools, we can now just do basic walkthroughs with rough recordings over codebase dictating what's going on along the way and then upload that to tools like AI Studio and then ask it to generate diagrams in a text-based format such as Mermaid that will then generate the flowcharts and diagrams for us. So this video walks us through this process of recording a rough video, uploading it to AI Studio and then asking AI Studio to generate the proper Mermaid diagram syntax.

Generate Mermaid Flow Chart Diagrams with Gemini 2.0 from Rough Screen Recordings

I'm a diehard Karabiner user and anytime I start doing something repetitively I always move it into my Karabiner configuration. Sometimes I'll fall into scenarios where I want to trigger a command, but I also want to know if that command succeeded or failed. Since Karabiner can trigger any command, setting up the command is fairly straightforward, but knowing whether it succeeded or failed became much more difficult. Luckily for me there is a package called terminal-notifier that you can install from homebrew and you can pipe the output of your command to terminal-notifier. And have a seamless way of triggering your keyboard shortcut which runs a command and you can be notified of the results.

Use Karabiner to Trigger a Terminal Command and Get Notified of the Results

There are a lot of scenarios when inspecting a site in Chrome where you don't want any click events to fire and you don't want any scripts to run. Or maybe something is animating in and out of the page and you want to capture it at a certain moment. This is a great use case for pausing script execution, which is kind of using the debugger manually by going into the Chrome DevTools and the Sources tab and clicking the pause button to essentially pause the entire page. This will give you a chance to inspect any of the elements and styles you want to inspect. And you don't have to worry about fire and click events or anything that might interrupt your investigation into the elements and styles that you want to find.

Pause Script Execution in Chrome to Easily Inspect Elements

Gemini 2.0 has a context window of a million tokens, and this means that you can upload hundreds of files and allow it to inspect and analyze massive refactors across entire code bases. 

This lesson demonstrates concatenating an entire code base into a single file and then uploading it to AI Studio. Once within AI Studio, we ask it to find the types of tasks that it can evaluate for us. Then we select one of the tasks and ask it to generate instructions for that task. Once those instructions are complete, we then turn them over to Windsurf's Cascade agent, and we allow Windsurf's Cascade to do all of the work for us as we sit back, relax, and let the AI do our jobs.

Ryan Harris

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