In this tutorial, we will build a snippet manager extension with React. A snippet manager is a tool used for storing and organizing commonly used pieces of code or text that can be quickly accessed.

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Prerequisites

This tutorial assumes that you have a basic knowledge and understanding of web development and React.

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Set up your Replit App

  1. Fork the Replit React Extension Template.
  2. Install the react-feather package with npm install react-feather.

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Configure the manifest file

Configure the title and description in public/extension.json (the Extension manifest file). 
{
  "name": "Snippet Manager",
  "description": "Easily access snippets of code directly within the Replit workspace",
  "version": "0",
  "tags": ["snippet", "manager", "tool"]
}
Add the tools property to extension.json and provide a tool that handles the / route of your application. This will allow your extension to appear as a tool in the sidebar. 
"tools": [
  {
    "handler": "/",
    "name": "Snippet Manager"
  }
]

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Build the Snippet Manager

Import the following dependencies in src/App.jsx 
import { useReplit, useReplitEffect } from "@replit/extensions-react";
import { replDb } from "@replit/extensions";
import { useState } from "react";
import "./App.css";
Remove all the existing code from the App function and add state variables snippets and newSnippetValue. snippets will store all of the snippets you’ve created and newSnippetValue will be a string for when you create a new snippet. 
function App() {
  const [snippets, setSnippets] = useState([]);
  const [newSnippetValue, setNewSnippetValue] = useState("");

  return (
    <main>
      <h1>Snippet Manager</h1>
    </main>
  );
}

​
Initialize the Handshake

Initialize the handshake and derive the status and error properties from the useReplit hook within the App function. The status property is an enumerated value indicating whether the handshake connection with Replit is loading, ready, or has resulted in an error. 
function App() {
  ...
  const { status, error } = useReplit();
  ...
}

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Handle Handshake Statuses

Handle the loading and error statuses from the useReplit hook. If the Extension is neither loading nor has resulted in an error, the main content will be rendered. 
function App() {
  ...

  if(status === 'error') {
    return <div className="screen">
      <h2>Error: {error.message}</h2>
    </div>
  }

  if(status === 'loading') {
    return <div className="screen">
      <h2>Loading...</h2>
    </div>
  }

  return <main>
    <h1>Snippet Manager</h1>
  </main>
}
Paste the following CSS code into src/App.css to apply basic styling to your exstension. If you refresh the extension, the snippets you’ve added will be saved. 
body {
  background-color: rgb(40, 40, 40);
  color: white;
  margin: 0;
  font-family: sans-serif;
}

main {
  padding: 16px;
  display: flex;
  flex-direction: column;
}

main h1 {
  margin-top: 0;
  margin-bottom: 16px;
}

.screen {
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

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Snippet Creation

Create an empty function insertSnippet within the App function. 
const insertSnippet = () => {};
Add the following JSX code into the App function after the h1 tag. This will be a basic form to create a new snippet. 
<div className="create-snippet-form">
  <textarea
    placeholder="Enter a new snippet here..."
    value={newSnippetValue}
    onChange={(e) => setNewSnippetValue(e.target.value)}
  ></textarea>
  <div>
    <button onClick={insertSnippet}>Add Snippet</button>
  </div>
</div>
Define an asynchronous function updateSnippets in App. This will allow us to update the snippets state variable and save it using the replDb module at the same time.
Values saved to a Replit App’s database get automatically URI-decoded so encoding has to happen twice. Replit App Databases can only store key-values as strings. Read More.
const updateSnippets = async (snippetsArr) => {
  setSnippets(snippetsArr);
  await replDb.set({
    key: "snippets",
    value: encodeURIComponent(snippetsArr.map(encodeURIComponent).join(",")),
  });
};
Back in the insertSnippet function, use the updateSnippets function to insert and save newSnippetValue to the list of snippets. 
const insertSnippet = () => {
  updateSnippets([...snippets, newSnippetValue]);
  setNewSnippetValue("");
};
Add the following CSS code into src/App.css to style the snippet creation form: 
.create-snippet-form {
  display: flex;
}

.create-snippet-form textarea {
  flex-grow: 1;
  margin-right: 8px;
}

textarea,
button {
  padding: 8px;
  background-color: rgb(90, 90, 90);
  border-radius: 8px;
  border: none;
  color: white;
  outline: none;
}

textarea:focus,
textarea:hover {
  border: none;
  outline: none;
  box-shadow: 0 0 0 2px #3273dc;
}

textarea::placeholder {
  color: rgb(200, 200, 200);
}

button {
  cursor: pointer;
}

button:focus,
button:hover {
  outline: none;
  background-color: #3273dc;
}

​
Load and list the snippets

Define an asynchronous function loadSnippets in App. This function will fetch all the snippets from the Replit database and update the snippets state variable. 
const loadSnippets = async () => {
  const snippetsFromDB = await replDb.get({
    key: "snippets",
  });

  if (snippetsFromDB) {
    setSnippets(snippetsFromDB.split(",").map(decodeURIComponent));
  }
};
Call the useReplitEffect hook to run the loadSnippets function once, when Replit successfully connects to your Extension. 
useReplitEffect(() => loadSnippets(), []);
Add the following code to the main UI after the .create-snippet-form element. Display each snippet as a paragraph from the snippet state variable. 
<div className="snippet-list">
  {snippets.map((snippet, index) => (
    <p key={index}>{snippet}</p>
  ))}
</div>
Install your extension, start creating some snippets, watch as they appear in realtime.

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The Snippet Component

You will be able to copy, edit, and delete snippets from the Snippet component with the click of a button. Create a file src/components/Snippet.jsx and import the following dependencies: 
import { messages } from "@replit/extensions";
import { Copy, Edit2, Trash } from "react-feather";
import { useState, useEffect } from "react";
Create and export the Snippet component. The props declared in this component are as follows:
  • content is the value of the snippet
  • index is a number signifying the index of the snippet
  • snippets is a full list of all the snippets in the database
  • updateSnippets is the asynchronous function passed down from the App component
Add two state variables isEditing and value. isEditing indicates whether the snippet is being edited and value is the new value which will be used when editing the snippet, before it is saved. 
export const Snippet = ({ content, index, snippets, updateSnippets }) => {
  const [isEditing, setIsEditing] = useState(false);
  const [value, setValue] = useState(content);

  return <div>Snippet Component</div>;
};
Add a useEffect hook to set value to content whenever content updates. The prop will change when snippets get edited and deleted. 
useEffect(() => setValue(content), [content]);
Create a function copyToClipboard. Handle the asynchronous clipboard event with the .then() and .catch() methods. Use the messages module to display whether the action was successful or not. 
const copyToClipboard = () => {
  window.navigator.clipboard
    .writeText(content)
    .then(async () => await messages.showConfirm("Copied to clipboard"))
    .catch(async (e) => await messages.showError(e.message));
};
Define a function saveEdit. This will update the current snippet to reflect the value state variable and save it to the database. 
const saveEdit = async () => {
  const snippetsArr = [...snippets];
  snippetsArr[index] = value;

  await updateSnippets(snippetsArr);
  setIsEditing(false);
};
Add a function deleteSnippet. After it is confirmed that the user wants to delete the snippet, remove the snippet from both the application state and the database. 
const deleteSnippet = async () => {
  const shouldDelete = confirm("Are you sure you want to delete this snippet?");

  if (shouldDelete) {
    const snippetsArr = [...snippets];
    snippetsArr.splice(index, 1);

    await updateSnippets(snippetsArr);
    await messages.showConfirm("Snippet Deleted");
  }
};
Complete the UI of the Snippet component with the following JSX code. If the snippet is being edited, a different component will be shown. 
return isEditing ? (
  <div className="snippet edit">
    <textarea value={value} onChange={(e) => setValue(e.target.value)} />
    <div className="snippet-button-row">
      <button onClick={() => setIsEditing(false)}>Cancel</button>
      <button onClick={saveEdit}>Save</button>
    </div>
  </div>
) : (
  <div className="snippet">
    <p>{content}</p>

    <div className="snippet-buttons">
      <button onClick={copyToClipboard}>
        <Copy />
      </button>

      <button onClick={() => setIsEditing(true)}>
        <Edit2 />
      </button>

      <button onClick={deleteSnippet}>
        <Trash />
      </button>
    </div>
  </div>
);
Apply the following CSS to src/App.css: 
.snippet {
  padding: 8px;
  background: rgb(70, 70, 70);
  margin-bottom: 8px;
  display: flex;
  padding: 8px;
  border-radius: 8px;
}

.snippet p {
  flex-grow: 1;
  margin: 0;
  padding: 0;
}

.snippet-buttons {
  display: flex;
}

.snippet-buttons button {
  margin-left: 8px;
}

.edit {
  flex-direction: column;
}

.edit textarea {
  margin-bottom: 8px;
}

.edit .snippet-button-row button {
  margin-right: 8px;
}

​
Display the snippets

In App.jsx, import the Snippet component. 
import { Snippet } from "./components/Snippet";
Update the .snippet-list div to render the new component. 
snippets.map((snippet, index) => (
  <Snippet
    key={index}
    content={snippet}
    snippets={snippets}
    updateSnippets={updateSnippets}
    index={index}
  />
));
Finally, style the snippet list with the following CSS: 
.snippet-list {
  flex-direction: column;
  display: flex;
  margin-top: 8px;
}
The Snippet Manager extension is now complete! Install it, open the Tools section on the sidebar, and select the Snippet Manager extension. You can now easily save and access your favorite snippets directly within your Replit App. See full solution