# Add an origin header to a CloudFront Functions viewer request event
Add an origin header

The following code example shows how to add an origin header to a CloudFront Functions viewer request event.

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#### [ JavaScript ]

**JavaScript runtime 2.0 for CloudFront Functions**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [CloudFront Functions examples](https://github.com/aws-samples/amazon-cloudfront-functions/tree/main/add-origin-header) repository. 

```
async function handler(event) {
    var request = event.request;
    var headers = request.headers;
    var host = request.headers.host.value;
   
   // If origin header is missing, set it equal to the host header.
   if (!headers.origin)
       headers.origin = {value:`https://${host}`};
       
   return request;
}
```

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For a complete list of AWS SDK developer guides and code examples, see [Using CloudFront with an AWS SDK](sdk-general-information-section.md). This topic also includes information about getting started and details about previous SDK versions.