type inference issue with dynamic template literals

🔎 Search Terms

"template literals and type inference", "type inference with dynamic template literals"

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about it

⏯ Playground Link

https://www.typescriptlang.org/play/?ts=5.4.5#code/C4TwDgpgBAgmCWUC8UDeAoKUDaBrCIAXFAAYAWEANpQPYB0AJKgM7ABO8AdgOYC+JAXWIAKACYBDYOOKooncQFsIxVhx5ReASmQA+KADca8Uel7p0lCMCgBXZhDYBJUSvZduyKAHJRIeQvgAYyhVdy9zAHoIqABRAA9FMEsARmIAERoIZk4vawB3GjZcOihQSCgAM0LSCBIoQPEc6wAjaC4KhzYIE0CaTlZSrOBU2ARPDCxscipaRlQ7B2d+IShoJD0JrHq+5hpLOlpuYQg6fwhNTA0AGlNI6PjEywAmYgB1QtxmdF7+62Ahl6jRAoTZTCjUeisSRBAD6oR4gmIaw2lywP12+0Ox1OinOl14NzM6CisQSCiSEAAzG8Pl90dY+p4ADwAaVWcX+nFEzCg+BANAqQJ0wkufOILJuWHEgWA8D6IgkUmIcHg2BZAm06wMRlEN01KKwJN2SighyCt3QfWE0whcwWTlE-Cuq10aEu6L2JyxJzOFy0QA

💻 Code

type Api = {
  [key: `hello.${string}`]: (data: { name: string }) => void
}

let userId: string = 'dynamic string'

// Example1: Doesn't work. type for `e` can't be inferred
const test1: Api = {
  [`hello.${userId}`]: e => {
    console.log(e.name)
  },
}

// Example2: Works
const test2: Api = {
  [`hello.static_string`]: e => {
    console.log(e.name)
  },
}

// Example3: Works
const on = <K extends keyof Api>(
  key: K,
  action: (data: Api[K]) => void,
) => {
  // some logic
}

on(`hello.${userId}`, e => {
  console.log(e.name)
})

🙁 Actual behavior

Example 1 doesn't work, while Example 2 and Example 3 works properly. The type for e can't be inferred

🙂 Expected behavior

To infer type of e in the Example 1.

Additional information about the issue

No response

Commencez par le TypeScript Playground lié et reproduisez le contraste entre les trois exemples, en particulier le typage contextuel de la propriété dynamique de template literal dans Example 1. Comparez le type inféré de e avec les cas de clé statique et de fonction générique ; c’est terminé lorsque Example 1 infère e comme le type de paramètre affiché { name: string }.