# Algorand TypeScript Language Server

The Algorand TypeScript language extension brings language server-powered capabilities to your smart contract authoring experience in Visual Studio Code. It extends the results from your installed TypeScript language server to provide Algorand TypeScript-specific diagnostics and code actions.

This tutorial demonstrates how to set up and use the Algorand Typescript extension to identify and resolve common issues early in your development workflow. We’ll walk through identifying and fixing bugs in an Algorand Typescript smart contract using the extension’s diagnostic features.

## Prerequisites

- [Visual Studio Code](https://code.visualstudio.com/download) 1.80.0 or higher
- [puya-ts](https://www.npmjs.com/package/@algorandfoundation/puya-ts) 1.0.1 or higher
- Basic understanding of [Algorand smart contracts using TypeScript](https://dev.algorand.co/concepts/smart-contracts/languages/typescript/)

## Step 1: Install the Extension

Install the Algorand TypeScript language extension from the VSCode Marketplace:

1. Open the Extensions view in VSCode (`Ctrl+Shift+X` or `Cmd+Shift+X`)
2. Search for `Algorand TypeScript`
3. Click `Install` on the extension published by the Algorand Foundation

Alternatively, install directly from the [marketplace](https://marketplace.visualstudio.com/items?itemName=AlgorandFoundation.algorand-typescript-vscode).

## Step 2: Set Up Your Project

### Initialize an AlgoKit Project

If you’re starting a new project, use AlgoKit to generate a TypeScript smart contract project:

```
algokit init
```

Select options for a TypeScript smart contract project from the interactive prompts.

If you haven’t installed algokit, follow these [steps](https://dev.algorand.co/getting-started/tutorials/get-ready-to-build).

### Install puya-ts

The extension requires `puya-ts` version `1.0.1` or higher. Install it as a dev dependency in your project:

```
npm install --save-dev @algorandfoundation/puya-ts
```

## Step 3: Enable the Language Server

For new AlgoKit projects, the language server is enabled by default. For existing projects, you need to enable it manually:

1. Open your workspace settings (`File` \> `Preferences` \> `Settings` or `Cmd+,`)
2. Search for `algorandTypeScript.languageServer.enable`
3. Check the box to enable the language server

Alternatively, add this to your `.vscode/settings.json`:

```
{

"algorandTypeScript.languageServer.enable": true

}
```

To see detailed information about what the language server is doing:

1. Open the `Output panel` (`View` \> `Output` or `Ctrl+Shift+U`)
2. Select `Algorand TypeScript Language Server` from the dropdown
3. Review logs for diagnostics and extension activity

## Step 4: Create an Example Smart Contract

Let’s create a simple contract with a deliberate bug to demonstrate the extension’s capabilities. Replace the Hello World contract with the below contract:

```typescript
import { BoxMap, clone, Contract, Txn } from '@algorandfoundation/algorand-typescript'

import { Address, DynamicArray, Uint64 } from '@algorandfoundation/algorand-typescript/arc4'

export class UserVotes extends Contract {

// Each user can vote for multiple proposals

votes = BoxMap<Address, DynamicArray<Uint64>>({ keyPrefix: '' })

castVote(proposalId: Uint64): DynamicArray<Uint64> {

const voter = new Address(Txn.sender)

if (this.votes(voter).exists) {

// Bug in line below: cannot create multiple references to a mutable stack type, the value must be copied using clone(...) when being assigned to another variable

const currentVotes = this.votes(voter).value

currentVotes.push(proposalId)

this.votes(voter).value = clone(currentVotes)

} else {

this.votes(voter).value = new DynamicArray(proposalId)

}

return this.votes(voter).value

}

}
```

This contract contains an intentional bug when updating the `current_vote` in the `cast_vote` function.

## Step 5: Observe Real-Time Diagnostics

Once you save the file, the Algorand TypeScript extension will analyze your code. You should see a red squiggly line under `current_votes` in the if condition.

The extension will display the error `cannot create multiple references to a mutable stack type, the value must be copied using clone(...) when being assigned to another variable` in the contract when you hover over the red line.

## Step 6: Apply Quick Fixes

The extension also provides quick fixes for the issue. Look for the lightbulb icon (💡) that appears. It suggests the fix `💡 Wrap expression in clone(...)`. Click on the suggestion to add the fix.

## Step 7: Fix the Smart Contract

Based on the extension’s diagnostics, your contract should now be updated as follows to address the identified issue:

```typescript
import { BoxMap, clone, Contract, Txn } from '@algorandfoundation/algorand-typescript'

import { Address, DynamicArray, Uint64 } from '@algorandfoundation/algorand-typescript/arc4'

export class UserVotes extends Contract {

// Each user can vote for multiple proposals

votes = BoxMap<Address, DynamicArray<Uint64>>({ keyPrefix: '' })

castVote(proposalId: Uint64): DynamicArray<Uint64> {

const voter = new Address(Txn.sender)

if (this.votes(voter).exists) {

// Bug Fixed in next line: wrapped expression in clone(...) when being assigned to another variable

const currentVotes = clone(this.votes(voter).value)

currentVotes.push(proposalId)

this.votes(voter).value = clone(currentVotes)

} else {

this.votes(voter).value = new DynamicArray(proposalId)

}

return this.votes(voter).value

}

}
```

## Step 8: Verify the Fixes

After applying the fixes, verify that warnings and errors have cleared in the Problems Panel. The extension will continue to provide real-time feedback as you progress in your development.

## Configuration Options

The extension provides additional configuration options for customizing your experience:

### Log Level

Adjust the verbosity of messages in the Output panel:

```
{

"algorandTypeScript.languageServer.logLevel": "info"

}
```

Available levels: `off`, `error`, `warn`, `info`, `debug`, `trace`

## Troubleshooting

If the extension isn’t working as expected:

### Extension Not Providing Diagnostics

1. Verify the extension is installed and enabled:
   - Check Extensions view for `Algorand TypeScript`
   - Ensure it shows as `Enabled`
2. Confirm the language server is enabled:
   - Check workspace settings for `algorandTypeScript.languageServer.enable`
   - Should be set to `true`
3. Verify puya-ts installation:

```
   npm list @algorandfoundation/puya-ts
```

- Ensure version `1.0.1` or higher is installed

### File Not Recognized

The extension only activates for `.algo.ts` files. Ensure your smart contract files use this extension.

### Conflicting Diagnostics

If you see duplicate or conflicting messages:
- The extension works alongside the standard TypeScript language server
- Some messages come from TypeScript, others from the Algorand extension
- Both sets of diagnostics are valuable for different aspects of your code

### Check Language Server Logs

1. Open Output panel (`View` \> `Output`)
2. Select `Algorand TypeScript Language Server` from dropdown
3. Look for error messages or warnings
4. Set log level to `debug` for more detailed information

## Summary

In this tutorial, we covered:

- Installing and configuring the Algorand TypeScript language extension
- Setting up a project with puya-ts
- Using real-time diagnostics to identify issues
- Applying quick fixes to resolve common problems
- Troubleshooting common extension issues

The Algorand TypeScript extension provides valuable assistance throughout your development process, helping you write more correct and robust smart contracts by catching issues early and suggesting improvements as you code.

## Next Steps

Learn Algorand TypeScript concepts, write and test smart contracts, debug with AVM Debugger, and follow best practices.

[Algorand TypeScript Concepts](https://dev.algorand.co/concepts/smart-contracts/languages/typescript) Explore Algorand TypeScript concepts

[Unit Tests](https://dev.algorand.co/algokit/unit-testing/typescript/overview) Learn about unit testing TypeScript contracts

[AVM Debugger](https://dev.algorand.co/algokit/avm-debugger) Try the AVM Debugger