Incorrect type declaration emitted for object with numeric string keys

[kazushisan]

🔎 Search Terms

numeric string key object

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ

⏯ Playground Link

https://www.typescriptlang.org/play?#code/MYewdgzgLgBAygFQIIIKpxgXhgbwFAyEwDaARACwAM5pAugFwylgiwBmIArmACal4BfGAEMIMUJCgBuPHigBPAA4BTeFGFROY7AGtl8kGxgKVh+MjRwgA

💻 Code

const STATUS = {
    ["404"]: "not found"
} as const;

type Status = keyof typeof STATUS;

🙁 Actual behavior

the type of Status will be the following.

type Status = "404"

however when I create a .d.ts file, the type of Status will not be the same. This is caused by the incorrect declare const in the declaration file that changes the numeric string keys to a number.

type Status = 404

🙂 Expected behavior

Given the example source code, the type for Status when referring to the declaration file will be the same as in the source code.

type Status = "404"

Note: this issue does not reproduce if the numeric string key used in the object is not a variable.

const STATUS = {
    "404": "not found"
} as const;

type Status = keyof typeof STATUS;
// type Status = "404"
// the result will be the same for both the source file and the type declaration file