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Guides /
Intro to Sway /
Typescript Frontend

Icon LinkBuilding the Frontend

Icon LinkSetup

Initialize a new React app with TypeScript in the same parent folder as your contract using the command below. 

npx create-react-app frontend --template typescript

Let's go into the frontend folder: 

cd frontend

Next, install the fuels TypeScript and wallet SDKs in the frontend folder: 

npm install fuels@0.73.0 @fuel-wallet/sdk@0.15.2 @fuel-wallet/react@0.15.2

Icon LinkGenerate contract types

The fuels init command generates a fuels.config.ts file that is used by the SDK to generate contract types. Use the contracts flag to define where your contract folder is located, and the output flag to define where you want the generated files to be created.

Run the command below in your frontend folder to generate the config file: 

npx fuels init --contracts ../contract/ --output ./src/contracts

Now that you have a fuels.config.ts file, you can use the fuels build command to rebuild your contract and generate types. Running this command will interpret the output ABI JSON from your contract and generate the correct TypeScript definitions. If you see the folder fuel-project/counter-contract/out you will be able to see the ABI JSON there.

Inside the fuel-project/frontend directory run: 

npx fuels build

A successful process should print and output like the following: 

Building..
Building Sway programs using built-in 'forc' binary
Generating types..
šŸŽ‰  Build completed successfully!
Icon InfoCircle

If you're having any issues with this part, try adding useBuiltinForc: false to your fuels.config.ts config file to make sure it's using the same version of forc as your default toolchain.

Now you should be able to find a new folder fuel-project/frontend/src/contracts.

Open the src/App.tsx file, and replace the boilerplate code with the template below: 

import { useState, useMemo } from "react";
import { useConnectUI, useIsConnected, useWallet } from "@fuel-wallet/react";
import { ContractAbi__factory } from "./contracts";
import AllItems from "./components/AllItems";
import ListItem from "./components/ListItem";
import "./App.css";
 
const CONTRACT_ID =
  "0x3b598fc9103ce3c5c7a29663aee51099b3374958ba1016280caf802fdeb5aad8";
 
function App() {
  const [active, setActive] = useState<"all-items" | "list-item">("all-items");
  const { isConnected } = useIsConnected();
  const { connect, isConnecting } = useConnectUI();
  const { wallet } = useWallet();
 
  const contract = useMemo(() => {
    if (wallet) {
      const contract = ContractAbi__factory.connect(CONTRACT_ID, wallet);
      return contract;
    }
    return null;
  }, [wallet]);
 
  return (
    <div className="App">
      <header>
        <h1>Sway Marketplace</h1>
      </header>
      <nav>
        <ul>
          <li
            className={active === "all-items" ? "active-tab" : ""}
            onClick={() => setActive("all-items")}
          >
            See All Items
          </li>
          <li
            className={active === "list-item" ? "active-tab" : ""}
            onClick={() => setActive("list-item")}
          >
            List an Item
          </li>
        </ul>
      </nav>
      <div>
        {isConnected ? (
          <div>
            {active === "all-items" && <AllItems contract={contract} />}
            {active === "list-item" && <ListItem contract={contract} />}
          </div>
        ) : (
          <div>
            <button
              onClick={() => {
                connect();
              }}
            >
              {isConnecting ? "Connecting" : "Connect"}
            </button>
          </div>
        )}
      </div>
    </div>
  );
}
 
export default App;

At the top of the file, change the CONTRACT_ID to the contract ID that you deployed earlier and set as a constant. 

const CONTRACT_ID =
  "0x3b598fc9103ce3c5c7a29663aee51099b3374958ba1016280caf802fdeb5aad8";

Copy and paste the CSS code below in your App.css file to add some simple styling. 

.App {
  text-align: center;
}
 
nav > ul {
  list-style-type: none;
  display: flex;
  justify-content: center;
  gap: 1rem;
  padding-inline-start: 0;
}
 
nav > ul > li {
  cursor: pointer;
}
 
.form-control{
  text-align: left;
  font-size: 18px;
  display: flex;
  flex-direction: column;
  margin: 0 auto;
  max-width: 400px;
}
 
.form-control > input {
  margin-bottom: 1rem;
}
 
.form-control > button {
  cursor: pointer;
  background: #054a9f;
  color: white;
  border: none;
  border-radius: 8px;
  padding: 10px 0;
  font-size: 20px;
}
 
.items-container{
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 2rem;
  margin: 1rem 0;
}
 
.item-card{
  box-shadow: 0px 0px 10px 2px rgba(0, 0, 0, 0.2);
  border-radius: 8px;
  max-width: 300px;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 4px;
}
 
.active-tab{
  border-bottom: 4px solid #77b6d8;
}
 
button {
  cursor: pointer;
  background: #054a9f;
  border: none;
  border-radius: 12px;
  padding: 10px 20px;
  margin-top: 20px;
  font-size: 20px;
  color: white;
}

Icon LinkConnecting to the contract

Wrap your components with FuelProvider from @fuel-wallet/react to enable Fuel's custom React hooks for wallet functionalities in index.tsx.

For development purposes devMode is also enabled here. This allows users to connect with the Fuel Development Wallet as well. 

import React from 'react';
import ReactDOM from 'react-dom/client';
import './index.css';
import App from './App';
import { FuelProvider } from '@fuel-wallet/react';
 
const root = ReactDOM.createRoot(
  document.getElementById('root') as HTMLElement
);
root.render(
  <React.StrictMode>
    <FuelProvider 
      fuelConfig={{
          devMode: true,
        }}
    >
    <App />
    </FuelProvider> 
  </React.StrictMode>
);

React hooks from the Fuel Wallet package are used in order to connect our wallet to the dapp. In the App function, we can call these hooks like this: 

const { isConnected } = useIsConnected();
const { connect, isConnecting } = useConnectUI();
const { wallet } = useWallet();

The wallet variable from the useWallet hook will have the type FuelWalletLocked.

You can think of a locked wallet as a user wallet you can't sign transactions for, and an unlocked wallet as a wallet where you have the private key and are able to sign transactions. 

const { wallet } = useWallet();

The useMemo hook is used to connect to our contract with the connected wallet. 

const contract = useMemo(() => {
  if (wallet) {
    const contract = ContractAbi__factory.connect(CONTRACT_ID, wallet);
    return contract;
  }
  return null;
}, [wallet]);
<div>
  {isConnected ? (
    <div>
      {active === "all-items" && <AllItems contract={contract} />}
      {active === "list-item" && <ListItem contract={contract} />}
    </div>
  ) : (
    <div>
      <button
        onClick={() => {
          connect();
        }}
      >
        {isConnecting ? "Connecting" : "Connect"}
      </button>
    </div>
  )}
</div>

Now we have our contract connection ready. You can console log the contract here to make sure this is working correctly.

Icon LinkUI

In our app we're going to have two tabs: one to see all of the items listed for sale, and one to list a new item for sale.

We use another state variable called active that we can use to toggle between our tabs. We can set the default tab to show all listed items. 

const [active, setActive] = useState<"all-items" | "list-item">("all-items");

Next we can create our components to show and list items.

Icon LinkListing an Item

Create a new folder in the src folder called components. 

mkdir components

Then create a file inside called ListItem.tsx. 

touch ListItem.tsx

At the top of the file, import the useState hook from react, the generated contract ABI from the contracts folder, and bn (big number) type from fuels. 

import { useState } from "react";
import { ContractAbi } from "../contracts";
import { bn } from "fuels";

This component will take the contract we made in App.tsx as a prop, so let's create an interface for the component. 

interface ListItemsProps {
  contract: ContractAbi | null;
}

We can set up the template for the function like this. 

export default function ListItem({contract}: ListItemsProps){

To list an item, we'll create a form where the user can input the metadata string and price for the item they want to list. Let's start by adding some state variables for the metadata and price. We can also add a status variable to track the submit status. 

const [metadata, setMetadata] = useState<string>("");
const [price, setPrice] = useState<string>("0");
const [status, setStatus] = useState<'success' | 'error' | 'loading' | 'none'>('none');

We need to add the handleSubmit function. We can use the contract prop to call the list_item function and pass in the price and metadata from the form. 

async function handleSubmit(e: React.FormEvent<HTMLFormElement>){
    e.preventDefault();
    setStatus('loading')
    if(contract !== null){
        try {
            const priceInput = bn.parseUnits(price.toString());
            await contract.functions
            .list_item(priceInput, metadata)
            .txParams({
                gasPrice: 1,
                gasLimit: 300_000,
            })
            .call();
            setStatus('success')
        } catch (e) {
            console.log("ERROR:", e);
            setStatus('error')
        }
    } else {
        console.log("ERROR: Contract is null");
    }
}

Under the heading, add the code below for the form: 

return (
        <div>
            <h2>List an Item</h2>
            {status === 'none' &&
            <form onSubmit={handleSubmit}>
                <div className="form-control">
                    <label htmlFor="metadata">Item Metadata:</label>
                    <input 
                        id="metadata" 
                        type="text" 
                        pattern="\w{20}" 
                        title="The metatdata must be 20 characters"
                        required 
                        onChange={(e) => setMetadata(e.target.value)}
                    />
                </div>
 
                <div className="form-control">
                    <label htmlFor="price">Item Price:</label>
                    <input
                        id="price"
                        type="number"
                        required
                        min="0"
                        step="any"
                        inputMode="decimal"
                        placeholder="0.00"
                        onChange={(e) => {
                          setPrice(e.target.value);
                        }}
                      />
                </div>
 
                <div className="form-control">
                    <button type="submit">List item</button>
                </div>
            </form>
            }
 
            {status === 'success' && <div>Item successfully listed!</div>}
            {status === 'error' && <div>Error listing item. Please try again.</div>}
            {status === 'loading' && <div>Listing item...</div>}
            
        </div>
    )
}

Now, try listing an item to make sure this works. You should see the message Item successfully listed!.

Icon LinkShow All Items

Next, let's create a new file called AllItems.tsx in the components folder. 

touch AllItems.tsx

Copy and paste the template code below for this component: 

import { useState, useEffect } from "react";
import { ContractAbi } from "../contracts";
import ItemCard from "./ItemCard";
import { BN } from "fuels";
import { ItemOutput } from "../contracts/contracts/ContractAbi";
 
interface AllItemsProps {
  contract: ContractAbi | null;
}
 
export default function AllItems({ contract }: AllItemsProps) {

Here we can get the item count to see how many items are listed, and then loop through each of them to get the item details.

First, let's create some state variables to store the number of items listed, an array of the item details, and the loading status. 

const [items, setItems] = useState<ItemOutput[]>([]);
const [itemCount, setItemCount] = useState<number>(0);
const [status, setStatus] = useState<"success" | "loading" | "error">(
  "loading"
);

Next, let's fetch the items in a useEffect hook. Because these are read-only functions, we can simulate a dry-run of the transaction by using the get method instead of call so the user doesn't have to sign anything. 

useEffect(() => {
  async function getAllItems() {
    if (contract !== null) {
      try {
        let { value } = await contract.functions
          .get_count()
          .txParams({
            gasPrice: 1,
            gasLimit: 100_000,
          })
          .simulate();
        let formattedValue = new BN(value).toNumber();
        setItemCount(formattedValue);
        let max = formattedValue + 1;
        let tempItems = [];
        for (let i = 1; i < max; i++) {
          let resp = await contract.functions
            .get_item(i)
            .txParams({
              gasPrice: 1,
              gasLimit: 100_000,
            })
            .simulate();
          tempItems.push(resp.value);
        }
        setItems(tempItems);
        setStatus("success");
      } catch (e) {
        setStatus("error");
        console.log("ERROR:", e);
      }
    }
  }
  getAllItems();
}, [contract]);

If the item count is greater than 0 and we are able to successfully load the items, we can map through them and display an item card.

The item card will show the item details and a buy button to buy that item, so we'll need to pass the contract and the item as props. 

return (
    <div>
      <h2>All Items</h2>
      {status === "success" && (
        <div>
          {itemCount === 0 ? (
            <div>Uh oh! No items have been listed yet</div>
          ) : (
            <div>
              <div>Total items: {itemCount}</div>
              <div className="items-container">
                {items.map((item) => (
                  <ItemCard
                    key={item.id.format()}
                    contract={contract}
                    item={item}
                  />
                ))}
              </div>
            </div>
          )}
        </div>
      )}
      {status === "error" && (
        <div>Something went wrong, try reloading the page.</div>
      )}
      {status === "loading" && <div>Loading...</div>}
    </div>
  );
}

Icon LinkItem Card

Now let's create the item card component. Create a new file called ItemCard.tsx in the components folder. 

touch ItemCard.tsx

After, copy and paste the template code below. 

import { useState } from "react";
import { ItemOutput } from "../contracts/contracts/ContractAbi";
import { ContractAbi } from "../contracts";
import { BN } from 'fuels';
 
interface ItemCardProps {
  contract: ContractAbi | null;
  item: ItemOutput;
}
 
const assetId = "0x0000000000000000000000000000000000000000000000000000000000000000"
 
export default function ItemCard({ item, contract }: ItemCardProps) {

Add a status variable to track the status of the buy button. 

const [status, setStatus] = useState<'success' | 'error' | 'loading' | 'none'>('none');

Create a new async function called handleBuyItem. Because this function is payable and transfers coins to the item owner, we'll need to do a couple special things here.

Whenever we call any function that uses the transfer or mint functions in Sway, we have to append the matching number of variable outputs to the call with the txParams method. Because the buy_item function just transfers assets to the item owner, the number of variable outputs is 1.

Next, because this function is payable and the user needs to transfer the price of the item, we'll use the callParams method to forward the amount. With Fuel you can transfer any type of asset, so we need to specify both the amount and the asset ID. 

async function handleBuyItem() {
  if (contract !== null) {
    setStatus('loading')
    try {
      await contract.functions.buy_item(item.id)
      .txParams({ 
        variableOutputs: 1,
        gasPrice: 1,
        gasLimit: 300_000,
      })
      .callParams({
          forward: [item.price, assetId],
        })
      .call()
      setStatus("success");
    } catch (e) {
      console.log("ERROR:", e);
    }
  }
}

Then add the item details and status messages to the card. 

return (
    <div className="item-card">
      <div>Id: {new BN(item.id).toNumber()}</div>
      <div>Metadata: {item.metadata}</div>
      <div>Price: {new BN(item.price).formatUnits()} ETH</div>
      <h3>Total Bought: {new BN(item.total_bought).toNumber()}</h3>
      {status === 'success' && <div>Purchased āœ…</div>}
      {status === 'error' && <div>Something went wrong āŒ</div>}
      {status === 'none' &&  <button data-testid={`buy-button-${item.id}`} onClick={handleBuyItem}>Buy Item</button>}
      {status === 'loading' && <div>Buying item..</div>}
    </div>
  );
}

Now you should be able to see and buy all of the items listed in your contract.

Icon LinkCheckpoint

Ensure that all your files are correctly configured by examining the code below. If you require additional assistance, refer to the repository here Icon Link

App.tsx 

import { useState, useMemo } from "react";
import { useConnectUI, useIsConnected, useWallet } from "@fuel-wallet/react";
import { ContractAbi__factory } from "./contracts";
import AllItems from "./components/AllItems";
import ListItem from "./components/ListItem";
import "./App.css";
 
const CONTRACT_ID =
  "0x3b598fc9103ce3c5c7a29663aee51099b3374958ba1016280caf802fdeb5aad8";
 
function App() {
  const [active, setActive] = useState<"all-items" | "list-item">("all-items");
  const { isConnected } = useIsConnected();
  const { connect, isConnecting } = useConnectUI();
  const { wallet } = useWallet();
 
  const contract = useMemo(() => {
    if (wallet) {
      const contract = ContractAbi__factory.connect(CONTRACT_ID, wallet);
      return contract;
    }
    return null;
  }, [wallet]);
 
  return (
    <div className="App">
      <header>
        <h1>Sway Marketplace</h1>
      </header>
      <nav>
        <ul>
          <li
            className={active === "all-items" ? "active-tab" : ""}
            onClick={() => setActive("all-items")}
          >
            See All Items
          </li>
          <li
            className={active === "list-item" ? "active-tab" : ""}
            onClick={() => setActive("list-item")}
          >
            List an Item
          </li>
        </ul>
      </nav>
      <div>
        {isConnected ? (
          <div>
            {active === "all-items" && <AllItems contract={contract} />}
            {active === "list-item" && <ListItem contract={contract} />}
          </div>
        ) : (
          <div>
            <button
              onClick={() => {
                connect();
              }}
            >
              {isConnecting ? "Connecting" : "Connect"}
            </button>
          </div>
        )}
      </div>
    </div>
  );
}
 
export default App;

AllItems.tsx 

import { useState, useEffect } from "react";
import { ContractAbi } from "../contracts";
import ItemCard from "./ItemCard";
import { BN } from "fuels";
import { ItemOutput } from "../contracts/contracts/ContractAbi";
 
interface AllItemsProps {
  contract: ContractAbi | null;
}
 
export default function AllItems({ contract }: AllItemsProps) {
  const [items, setItems] = useState<ItemOutput[]>([]);
  const [itemCount, setItemCount] = useState<number>(0);
  const [status, setStatus] = useState<"success" | "loading" | "error">(
    "loading"
  );
  useEffect(() => {
    async function getAllItems() {
      if (contract !== null) {
        try {
          let { value } = await contract.functions
            .get_count()
            .txParams({
              gasPrice: 1,
              gasLimit: 100_000,
            })
            .simulate();
          let formattedValue = new BN(value).toNumber();
          setItemCount(formattedValue);
          let max = formattedValue + 1;
          let tempItems = [];
          for (let i = 1; i < max; i++) {
            let resp = await contract.functions
              .get_item(i)
              .txParams({
                gasPrice: 1,
                gasLimit: 100_000,
              })
              .simulate();
            tempItems.push(resp.value);
          }
          setItems(tempItems);
          setStatus("success");
        } catch (e) {
          setStatus("error");
          console.log("ERROR:", e);
        }
      }
    }
    getAllItems();
  }, [contract]);
  return (
    <div>
      <h2>All Items</h2>
      {status === "success" && (
        <div>
          {itemCount === 0 ? (
            <div>Uh oh! No items have been listed yet</div>
          ) : (
            <div>
              <div>Total items: {itemCount}</div>
              <div className="items-container">
                {items.map((item) => (
                  <ItemCard
                    key={item.id.format()}
                    contract={contract}
                    item={item}
                  />
                ))}
              </div>
            </div>
          )}
        </div>
      )}
      {status === "error" && (
        <div>Something went wrong, try reloading the page.</div>
      )}
      {status === "loading" && <div>Loading...</div>}
    </div>
  );
}

ItemCard.tsx 

import { useState } from "react";
import { ItemOutput } from "../contracts/contracts/ContractAbi";
import { ContractAbi } from "../contracts";
import { BN } from 'fuels';
 
interface ItemCardProps {
  contract: ContractAbi | null;
  item: ItemOutput;
}
 
const assetId = "0x0000000000000000000000000000000000000000000000000000000000000000"
 
export default function ItemCard({ item, contract }: ItemCardProps) {
  const [status, setStatus] = useState<'success' | 'error' | 'loading' | 'none'>('none');
  async function handleBuyItem() {
    if (contract !== null) {
      setStatus('loading')
      try {
        await contract.functions.buy_item(item.id)
        .txParams({ 
          variableOutputs: 1,
          gasPrice: 1,
          gasLimit: 300_000,
        })
        .callParams({
            forward: [item.price, assetId],
          })
        .call()
        setStatus("success");
      } catch (e) {
        console.log("ERROR:", e);
      }
    }
  }
  return (
    <div className="item-card">
      <div>Id: {new BN(item.id).toNumber()}</div>
      <div>Metadata: {item.metadata}</div>
      <div>Price: {new BN(item.price).formatUnits()} ETH</div>
      <h3>Total Bought: {new BN(item.total_bought).toNumber()}</h3>
      {status === 'success' && <div>Purchased āœ…</div>}
      {status === 'error' && <div>Something went wrong āŒ</div>}
      {status === 'none' &&  <button data-testid={`buy-button-${item.id}`} onClick={handleBuyItem}>Buy Item</button>}
      {status === 'loading' && <div>Buying item..</div>}
    </div>
  );
}

ListItem.tsx 

import { useState } from "react";
import { ContractAbi } from "../contracts";
import { bn } from "fuels";
 
interface ListItemsProps {
  contract: ContractAbi | null;
}
 
export default function ListItem({contract}: ListItemsProps){
    const [metadata, setMetadata] = useState<string>("");
    const [price, setPrice] = useState<string>("0");
    const [status, setStatus] = useState<'success' | 'error' | 'loading' | 'none'>('none');
    async function handleSubmit(e: React.FormEvent<HTMLFormElement>){
        e.preventDefault();
        setStatus('loading')
        if(contract !== null){
            try {
                const priceInput = bn.parseUnits(price.toString());
                await contract.functions
                .list_item(priceInput, metadata)
                .txParams({
                    gasPrice: 1,
                    gasLimit: 300_000,
                })
                .call();
                setStatus('success')
            } catch (e) {
                console.log("ERROR:", e);
                setStatus('error')
            }
        } else {
            console.log("ERROR: Contract is null");
        }
    }
    return (
        <div>
            <h2>List an Item</h2>
            {status === 'none' &&
            <form onSubmit={handleSubmit}>
                <div className="form-control">
                    <label htmlFor="metadata">Item Metadata:</label>
                    <input 
                        id="metadata" 
                        type="text" 
                        pattern="\w{20}" 
                        title="The metatdata must be 20 characters"
                        required 
                        onChange={(e) => setMetadata(e.target.value)}
                    />
                </div>
 
                <div className="form-control">
                    <label htmlFor="price">Item Price:</label>
                    <input
                        id="price"
                        type="number"
                        required
                        min="0"
                        step="any"
                        inputMode="decimal"
                        placeholder="0.00"
                        onChange={(e) => {
                          setPrice(e.target.value);
                        }}
                      />
                </div>
 
                <div className="form-control">
                    <button type="submit">List item</button>
                </div>
            </form>
            }
 
            {status === 'success' && <div>Item successfully listed!</div>}
            {status === 'error' && <div>Error listing item. Please try again.</div>}
            {status === 'loading' && <div>Listing item...</div>}
            
        </div>
    )
}

Icon LinkRun your project

Inside the fuel-project/frontend directory run: 

npm start
Compiled successfully!

You can now view frontend in the browser.

  Local:            http://localhost:3000
  On Your Network:  http://192.168.4.48:3000

Note that the development build is not optimized.
To create a production build, use npm run build.

And that's it for the frontend! You just created a whole dapp on Fuel!