How does readFile option work?

[thetutlage]

I have been searching Typescript documentation and also other opened issues in this repo. Have not been able to find how exactly readFile option works

If I use the following code

require('ts-node').register({
  readFile: function foo (file) {
    console.log({ readFile: file })
    return typescript.sys.readFile(file)
  },
})

It does resolve initial files like tsconfig or type definitions. However, the import statements of my application code are not getting through this function?

Do they go directly to Node.js require or how exactly it works?

[thetutlage]

Okay, it does come to the readFile hook. The ts-node internal cache wasn't executing it if source files were same.