CORS for AWS Lambda using Serverless Framework

CORS.js

// Because I can never remember the precise syntax and the Serverless Framework docs are out of date (at least when I wrote this)...

// Handler.js
resSuccess(data = {}, statusCode = 200) {
    return {
      statusCode,
      body: JSON.stringify(data),
      headers: {
        "Content-Type": "application/json",
        "Access-Control-Allow-Headers": "*",
        "Access-Control-Allow-Origin": "*", 
        "Access-Control-Allow-Methods": "OPTIONS,POST,GET,PUT",
      },
    };
  }


// Serverless.yml
provider:
  name: aws
  region: ${env:AWS_LAMBDA_REGION}
  stage: ${env:AWS_STAGE}
  runtime: nodejs14.x
  stackName: <redacted>-${env:AWS_STAGE}
  apiName: rest-<redacted>
  memorySize: 512
  timeout: 6
  websocketsApiName: ws-<redacted>
  websocketsApiRouteSelectionExpression: $request.body.action
  iamRoleStatements:
    - Effect: 'Allow'
      Action:
        - dynamodb:PartiQLInsert
        - dynamodb:PartiQLUpdate
        - dynamodb:PartiQLSelect
      Resource: 'arn:aws:dynamodb:<redacted>'
  httpApi:
    cors: true