Basic

Function setup

Create these files then push to trigger a Netlify build.

netlify.toml. The build command must be set - the docs recommend a comment if you have nothing else.
```
  [build]
    functions = "functions"
    command = "#"
```

functions/hello.js. (Or at functions/hello/index.js Or functions/hello/hello.js.)

  exports.handler = function (event) {
      const respData = {
        message: "Hello World"
        eventData: event
      }
        
      return {
          statusCode: 200,
          body: JSON.stringify(respData)
      };
  }

Use query parameters like ?myParam=foo.

const myParam = event.queryStringParameters.myParam;

Testing

Then when deployed you query the Lambda at a path like /.netlify/functions/hello.

https://example.netlify.com/.netlify/functions/hello
```
  {"message": "Hello World"}
```

Breakdown of the URL:

/.netlify/functions - this is a fixed path and cannot be configured.
hello is based on the JS script name.