Development environment Type definitions for Lambda

Building Lambda functions with TypeScript

You can use the Node.js runtime to run TypeScript code in AWS Lambda. Because Node.js doesn't run TypeScript code natively, you must first transpile your TypeScript code into JavaScript. Then, use the JavaScript files to deploy your function code to Lambda. Your code runs in an environment that includes the AWS SDK for JavaScript, with credentials from an AWS Identity and Access Management (IAM) role that you manage. To learn more about the SDK versions included with the Node.js runtimes, see Runtime-included SDK versions.

Lambda supports the following Node.js runtimes.

Name Identifier Operating system Deprecation date Block function create Block function update

Node.js 24	nodejs24.x	Amazon Linux 2023	Apr 30, 2028	Jun 1, 2028	Jul 1, 2028
Node.js 22	nodejs22.x	Amazon Linux 2023	Apr 30, 2027	Jun 1, 2027	Jul 1, 2027

Topics

Setting up a TypeScript development environment

Use a local integrated development environment (IDE) or text editor to write your TypeScript function code. You can’t create TypeScript code on the Lambda console.

You can use either esbuild or Microsoft's TypeScript compiler (tsc) to transpile your TypeScript code into JavaScript. The AWS Serverless Application Model (AWS SAM) and the AWS Cloud Development Kit (AWS CDK) both use esbuild.

When using esbuild, consider the following:

There are several TypeScript caveats.
You must configure your TypeScript transpilation settings to match the Node.js runtime that you plan to use. For more information, see Target in the esbuild documentation. For an example of a tsconfig.json file that demonstrates how to target a specific Node.js version supported by Lambda, refer to the TypeScript GitHub repository.
esbuild doesn’t perform type checks. To check types, use the tsc compiler. Run tsc -noEmit or add a "noEmit" parameter to your tsconfig.json file, as shown in the following example. This configures tsc to not emit JavaScript files. After checking types, use esbuild to convert the TypeScript files into JavaScript.

Example tsconfig.json

{ "compilerOptions": { "target": "es2020", "strict": true, "preserveConstEnums": true, "noEmit": true, "sourceMap": false, "module":"commonjs", "moduleResolution":"node", "esModuleInterop": true, "skipLibCheck": true, "forceConsistentCasingInFileNames": true, "isolatedModules": true, }, "exclude": ["node_modules", "**/*.test.ts"] }

Type definitions for Lambda

The @types/aws-lambda package provides type definitions for Lambda functions. Install this package when your function uses any of the following:

Common AWS event sources, such as:
- APIGatewayProxyEvent: For Amazon API Gateway proxy integrations
- SNSEvent: For Amazon Simple Notification Service notifications
- SQSEvent: For Amazon Simple Queue Service messages
- S3Event: For S3 trigger events
- DynamoDBStreamEvent: For Amazon DynamoDB Streams
The Lambda Context object
The callback handler pattern

To add the Lambda type definitions to your function, install @types/aws-lambda as a development dependency:

npm install -D @types/aws-lambda

Then, import the types from aws-lambda:

import { Context, S3Event, APIGatewayProxyEvent } from 'aws-lambda'; export const handler = async (event: S3Event, context: Context) => { // Function code };

The import ... from 'aws-lambda' statement imports the type definitions. It does not import the aws-lambda npm package, which is an unrelated third-party tool. For more information, see aws-lambda in the DefinitelyTyped GitHub repository.

Note

You don't need @types/aws-lambda when using your own custom type definitions. For an example function that defines its own type for an event object, see Example TypeScript Lambda function code.

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