AWS SAM local start-api: Set lambda nodejs 12.x flags (e.g. --experimental-modules)?

Question

I use ES6 module syntax on my nodejs server:

package.json

"type": "module"

I (successfully) run my server as local nodejs process. E.g.:

"scripts": {
  "dev": "npm outdated ; nodemon --experimental-modules --inspect=4001 main.local.js"
}

Problem: If I start my server via sam local:

"scripts": {
  "dev-sam": "sam local start-api --skip-pull-image",
}

I get an error:

Warning: require() of ES modules is not supported. 
require() of /var/task/main.js from /var/runtime/UserFunction.js is an ES module file 
as it is a .js file whose nearest parent package.jsoncontains "type": "module" which 
defines all .js files in that package scope as ES modules.
Instead rename main.js to end in .cjs, change the requiring code to use import(), or 
remove "type": "module" from /var/task/package.json.

My conclusion is: I need to tell the nodejs runtime to enable experimental es6 module support.

Question: How do I do that?

Tried (not working):

"scripts": {
  "dev-sam": "sam local start-api --experimental-modules --skip-pull-image",
}

Answer 1

You can't pass arguments to lambda environments. You need to use transpiler. Compile your lambda functions with webpack or similar transpiler.