Characters count as both prefix and suffix of pattern literal #40772

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1. Andrew Branch (andrewbranch)

   added

   BugA bug in TypeScriptA bug in TypeScript

   on Sep 25, 2020
2. Andrew Branch (andrewbranch)

   added this to the TypeScript 4.1.1 milestone on Sep 25, 2020
3. Andrew Branch (andrewbranch)

   assigned

   Wesley Wigham (weswigham)

   on Sep 25, 2020
4. jamesmfriedman commented on Sep 28, 2020

   

   James Friedman (jamesmfriedman)

   on Sep 28, 2020

   More actions

   Related to this issue,

   • It's great that in dev you can use string as a value placeholder! This is a marked improvement from beta.
   • The ability to define a prefix or suffix for a key is very valuable, but currently neither of these usecases work:

   type CustomProps = Record<`x${string}`, any>;
   const a: CustomProps = {};
   a.x11 = ''; // ERRORS OUT
   
   type CustomProps ={[key: `x${string}`]:  any}; // ERRORS, key must be string or number
   const a: CustomProps = {};
   

   Would be amazing if this could work!
5. TypeScript Bot (typescript-bot)

   added

   Fix AvailableA PR has been opened for this issueA PR has been opened for this issue

   on Sep 29, 2020
6. Wesley Wigham (weswigham)

   closed this as completedin #40841on Sep 29, 2020
7. microsoft

   locked as resolved and limited conversation to collaborators on Oct 21, 2025