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İnanç Akduvan
İnanç Akduvan

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Connect MetaMask wallet #JavaScript

#web3 #javascript #metamask #webdev

We will connect MetaMask wallet and get accounts with javascript basically.

Try demo here:
https://inancakduvan.github.io/connect-metamask-wallet/

Find source code on github:
https://github.com/inancakduvan/connect-metamask-wallet

1) Check if MetaMask plugin installed on browser
If not, redirect user to MetaMask download page.

const connectButton = document.getElementById("connectButton"); connectButton.addEventListener("click", () => { if (typeof window.ethereum !== "undefined") { console.log("MetaMask installed") } else { window.open("https://metamask.io/download/", "_blank"); } })
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2) Get accounts if MetaMask installed
MetaMask plugin will automatically open when we send a request to get accounts.

const connectButton = document.getElementById("connectButton"); const walletID = document.getElementById("walletID"); if (typeof window.ethereum !== "undefined") { ethereum .request({ method: "eth_requestAccounts" }) .then((accounts) => { const account = accounts[0] walletID.innerHTML = `Wallet connected: ${account}`; }) } else { window.open("https://metamask.io/download/", "_blank"); }
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3) Handle errors
Handling errors is a good practise to guide the user correctly.
(For example: show a loader while user is connecting wallet and hide it if user cancel process)

const connectButton = document.getElementById("connectButton"); const walletID = document.getElementById("walletID"); connectButton.addEventListener("click", () => { if (typeof window.ethereum !== "undefined") { ethereum .request({ method: "eth_requestAccounts" }) .then((accounts) => { const account = accounts[0] walletID.innerHTML = `Wallet connected: ${account}`; }).catch((error) => { // Handle error console.log(error, error.code); // 4001 - The request was rejected by the user // -32602 - The parameters were invalid // -32603- Internal error }); } else { window.open("https://metamask.io/download/", "_blank"); } })
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It is done here, we can say. But if you are interested in some extra suggestions, keep reading:

EXTRA SUGGESTIONS

4) Show a loader while user is connecting wallet via plugin

const connectButton = document.getElementById("connectButton"); const walletID = document.getElementById("walletID"); connectButton.addEventListener("click", () => { // Start loader while connecting connectButton.classList.add("loadingButton"); if (typeof window.ethereum !== "undefined") { ethereum .request({ method: "eth_requestAccounts" }) .then((accounts) => { const account = accounts[0] walletID.innerHTML = `Wallet connected: ${account}`; // Stop loader when connected connectButton.classList.remove("loadingButton"); }).catch((error) => { // Handle error console.log(error, error.code); // Stop loader if error occured connectButton.classList.remove("loadingButton"); // 4001 - The request was rejected by the user // -32602 - The parameters were invalid // -32603- Internal error }); } else { window.open("https://metamask.io/download/", "_blank"); } })
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5) Show a "Reload page" warning when user is redirected to download page
User needs to refresh page after plugin installed and so browser can re-fetch scripts. It would be a good practise to let user know about this.

const connectButton = document.getElementById("connectButton"); const walletID = document.getElementById("walletID"); const reloadButton = document.getElementById("reloadButton"); const installAlert = document.getElementById("installAlert"); connectButton.addEventListener("click", () => { // Start loader while connecting connectButton.classList.add("loadingButton"); if (typeof window.ethereum !== "undefined") { ethereum .request({ method: "eth_requestAccounts" }) .then((accounts) => { const account = accounts[0] walletID.innerHTML = `Wallet connected: ${account}`; // Stop loader when connected connectButton.classList.remove("loadingButton"); }).catch((error) => { // Handle error console.log(error, error.code); // Stop loader if error occured // For example, when user cancelled request  // and closed plugin connectButton.classList.remove("loadingButton"); // 4001 - The request was rejected by the user // -32602 - The parameters were invalid // -32603- Internal error }); } else { window.open("https://metamask.io/download/", "_blank"); // Show 'Reload page' warning to user installAlert.classList.add("show"); } }) // Reload the page on reload button click reloadButton.addEventListener("click", () => { window.location.reload(); });
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6) Check if user is on mobile device
If user is on mobile device, MetaMask application's browser should be used to be connected.

const connectButton = document.getElementById("connectButton"); const walletID = document.getElementById("walletID"); const reloadButton = document.getElementById("reloadButton"); const installAlert = document.getElementById("installAlert"); const mobileDeviceWarning = document.getElementById("mobileDeviceWarning"); connectButton.addEventListener("click", () => { // Start loader while connecting connectButton.classList.add("loadingButton"); if (typeof window.ethereum !== "undefined") { ethereum .request({ method: "eth_requestAccounts" }) .then((accounts) => { const account = accounts[0] walletID.innerHTML = `Wallet connected: ${account}`; // Stop loader when connected connectButton.classList.remove("loadingButton"); }).catch((error) => { // Handle error console.log(error, error.code); // Stop loader if error occured // For example, when user cancelled request  // and closed plugin connectButton.classList.remove("loadingButton"); // 4001 - The request was rejected by the user // -32602 - The parameters were invalid // -32603- Internal error }); } else { // Find the function which checks if device is mobile // at my github repo or anywhere if (isMobile()) { mobileDeviceWarning.classList.add("show"); } else { window.open("https://metamask.io/download/", "_blank"); // Show 'Reload page' warning to user installAlert.classList.add("show"); } } }) // Reload the page on reload button click reloadButton.addEventListener("click", () => { window.location.reload(); });
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Here is html and css:

 <div class="container"> <button class="button" id="connectButton"> Connect wallet <span id="loading"> <span>&bull;</span><span>&bull;</span><span>&bull;</span> </span> </button> <div id="walletID">Your wallet is not connected yet.</div> <div id="mobileDeviceWarning"> If you are on a mobile phone, please use MetaMask application's browser to connect. </div> </div> <div class="alert" id="installAlert"> Please refresh your browser after installing the Metamask plugin <button class="button" id="reloadButton">Reload page</button> </div>
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.container { position: relative; display: flex; flex-direction: column; align-items: center; justify-content: center; width: 100%; height: 100vh; } .button { position: relative; display: flex; align-items: center; justify-content: center; border: none; outline: none; box-shadow: 0 1px 5px 0 #e6e9ef; background: #ffffff; color: #000; border-radius: 99px; padding: 16px 32px; font-family: 'Quicksand', sans-serif; font-size: 24px; font-weight: 500; cursor: pointer; } #connectButton { margin-bottom: 16px; color: #eb874b; } #walletID span{ max-width: 90%; margin: 0 auto; font-size: 12px; font-weight: 600; } #mobileDeviceWarning { display: none; margin-top: 24px; color: rgb(247, 47, 47); } #mobileDeviceWarning.show { display: block; } .alert { z-index: 10; position: fixed; left: 0; top: 0; display: none; flex-direction: column; align-items: center; justify-content: center; width: 100%; height: 100vh; background: #ffffff; } .alert.show { display: flex; } .alert .button { margin-top: 24px; } /* Loading dots styles */ @keyframes opacity { 0% { opacity: 1; } 100% { opacity: 0; } } .loadingButton { pointer-events: none; } .loadingButton #loading { display: flex; } #loading { position: absolute; top: 0; left: 0; width: 100%; height: 100%; display: none; align-items: center; justify-content: center; background: #fff; border-radius: 99px; } #loading span:not(:last-child) { margin-right: 5px; } #loading span { animation-name: opacity; animation-duration: 1s; animation-iteration-count: infinite; } #loading span:nth-child(2) { animation-delay: 100ms; animation-delay: 100ms; } #loading span:nth-child(3) { animation-delay: 300ms; animation-delay: 300ms; }
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Find source code on github:
https://github.com/inancakduvan/connect-metamask-wallet

Follow me on:

Github: https://github.com/inancakduvan/
Twitter: https://twitter.com/InancAkduvan

Thank you for reading 🙂

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