Introduction to Node.js

What is Node.js?

A JavaScript runtime environment that allows you to run JavaScript code on the server instead of in a browser.

Why do we use Node.js in Lambda?

Because Lambda supports Node.js natively, allowing JavaScript code to run serverlessly without managing servers.

What is a Lambda Function?

A small, serverless function hosted by AWS that runs your code only when triggered (e.g., by API Gateway).

Where will you develop and test your Lambda code?

In the AWS Lambda Console using the built in code editor and Test button.

Where does your Lambda code run?

On AWS-managed infrastructure in the cloud, only when triggered.

Structure of a Lambda handler

export const handler = async (event) => { return response; };

What is the event object?

A JSON structure containing all input sent to the Lambda (parameters, body, headers).

What does JSON.stringify do?

Converts JavaScript objects/strings into JSON-formatted strings required in Lambda responses.

What is a Lambda response object?

An object with statusCode and body fields, where body must be a string.

What does += mean?

Addition assignment operator; x += y is the same as x = x + y.

What does a for loop do?

Repeats code while incrementing or decrementing a counter until a condition is false.

Where do console.log outputs appear?

In CloudWatch Logs for each Lambda function.

Why return JSON in Lambda?

APIs expect structured JSON so browser JavaScript can parse it easily.

What is serverless computing?

Running code without managing servers. AWS automatically handles execution.

When does code run in a Lambda function?

Code in an AWS Lambda function runs in response to an event

What does Async do

makes a function run asynchronously so it can WAIT for things like database queries or API calls without freezing.