typescriptts-morph

How to get the value of a (TypeScript) template literal type programatically?

I'm trying to get the value of a template literal type. I know I have to parse the source file for this. I am using ts-morph right now which basically extends the programmatic API of the TypeScript compiler. But I am open to other options of how to get the value of template literal types.

Here is an example of what I am trying to do:

import { Project } from 'ts-morph'

const sourceFile = project.createSourceFile('source.ts', `
type Hello = 'hello'
`)

const typeAlias = sourceFile.addTypeAlias({
  name: `MyTemplateLiteralType`,
  type: '${Hello} world'
})

console.log(typeAlias.getType().getLiteralValue()) // "hello world"

Note the getLiteralValue() does not work for template literals, but I am looking for something similar that does.

Solution

  • I found the solution. You cannot retrieve it from the return value of addTypeAlias. Instead, I had to do:

    sourceFile.getTypeAliasOrThrow('MyTemplateLiteralType').getType().getLiteralValue()