Add missing `toString` declarations for base types that have them

Search Terms

toString, RegExp, Regular Expression, Boolean, Error

Suggestion

In @typescript-eslint, we have a rule no-base-to-string. This rule ensures that any value that's being coerced to a string has a toString method defined on it.
This is to help catch cases where you accidentally coerce something to a string, and end up with an [object Object] in your strings.

This rule has a pretty simple implementation - it just gets the declarations of the toString method on the type, and ensures that none of the declarations belong to the Object type.
The logic relies upon the fact that every type that actually has a toString method explicitly declares a toString method.

A few of our users ran into cases that were reporting errors for them, even though they shouldn't (https://github.com/typescript-eslint/typescript-eslint/issues/1655).
There's one that specifically has caused people some issues: Boolean/boolean.

I eyeballed the docs and the types, and I am pretty certain there are only 3 types that are missing a toString declaration:

• RegExp: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/toString
• Boolean: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean/toString
• Error: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/toString

Related

PR: #37839

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

まず、RegExp、Boolean、Error の標準ライブラリ宣言を見つけ、既存のメンバーを対応する JavaScript 組み込みと比較します。欠落している各 toString 宣言が型に表現されていることを確認し、関連する TypeScript テストスイートで変更を検証します。完了の条件は、3 つすべての型がメソッドを明示的に宣言し、出力される JavaScript を変更していないことです。