ReferenceError: require is not defined in ES module scope, you can use import instead

Question

Trying to follow a DynamoDB + Lambda + API Gateway tutorial: [http-api-dynamo-db](https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api-dynamo-db.html).
```
const AWS = require("aws-sdk");
const dynamo = new AWS.DynamoDB.DocumentClient();
```
These above lines in the lambda function result in a "ReferenceError":

```
{
  "errorType": "ReferenceError",
  "errorMessage": "require is not defined in ES module scope, you can use import instead",
  "trace": [
    "ReferenceError: require is not defined in ES module scope, you can use import instead",
    "    at file:///var/task/index.mjs:1:13",
    "    at ModuleJob.run (node:internal/modules/esm/module_job:193:25)",
    "    at async Promise.all (index 0)",
    "    at async ESMLoader.import (node:internal/modules/esm/loader:530:24)",
    "    at async _tryAwaitImport (file:///var/runtime/index.mjs:921:16)",
    "    at async _tryRequire (file:///var/runtime/index.mjs:970:86)",
    "    at async _loadUserApp (file:///var/runtime/index.mjs:994:16)",
    "    at async UserFunction.js.module.exports.load (file:///var/runtime/index.mjs:1035:21)",
    "    at async start (file:///var/runtime/index.mjs:1200:23)",
    "    at async file:///var/runtime/index.mjs:1206:1"
  ]
}
```
How to resolve it? and what is causing this issue? Thanks.

Accepted Answer

This is seen if you are using NodeJS 14 or above which no longer has `require` by default. See https://nodejs.org/api/esm.html#no-require-exports-or-moduleexports

You can fix this by adding these two lines at the top of your file.

```
import { createRequire } from 'module';
const require = createRequire(import.meta.url);
```

Answer

**SDK V2**
```
const AWS = require("aws-sdk");

const dynamo = new AWS.DynamoDB.DocumentClient();
```

**SDK V3**
```
const {DynamoDB} = require("@aws-sdk/client-dynamodb");

const dynamo = new DynamoDB({});
```

**Backward V2 Compatibility Style**

```
import * as AWS from "@aws-sdk/client-dynamodb";

const dynamo = new AWS.DynamoDB({});
```

See 
https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/welcome.html

Answer

I only got it to work with Node 18 after
1. installing the DynamoDB client in Cloudshell with
```
npm install @aws-sdk/client-dynamodb
```
from https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/installing-jssdk.html

2. changing the code to
```
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import { PutCommand, DynamoDBDocumentClient } from "@aws-sdk/lib-dynamodb";

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

/**
 * Returns an HTML page containing an interactive Web-based tutorial.
 * Visit the function URL to see it and learn how to build with lambda.
 */
export const handler = async (event) => {
    if(event.queryStringParameters){
        const command = new PutCommand({
            TableName: "formStore",
            Item: {
              PK: "form",
              SK: event.requestContext.requestId,
              form: event.queryStringParameters
            }
        });
        const response = await docClient.send(command);
        console.log(response);
    }
```
from
https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/javascript_dynamodb_code_examples.html#actions

3. creating the `formStore` table in AWS Dynamo DB with `PK` as partition key and `SK` as sort key and adding the `dynamoDB:PutItem` permission to the IAM Role of my Lambda function
```
To add the dynamoDb:PutItem permission to the IAM role of your Lambda function:
1. Open the IAM console and navigate to the role used by your Lambda function (link) .
2. Click on the "Permissions" tab.
3. Click "Create inline policy".
4. Choose "DynamoDB" as the service.
5. In the "Actions" search box, type "PutItem" and select it.
6. For the "Resources" field, specify the ARN of your DynamoDB table (e.g. arn:aws:dynamodb:region:account-id:table/table-name).
7. Click "Review Policy" then "Create Policy".
```

ReferenceError: require is not defined in ES module scope, you can use import instead

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