If you declare a variable but never use it, TypeScript will not compile, saying '<variable>' is declared but its value is never read.

That error will not go away until you use that variable somewhere.

If this happens on a single line, you can use the line // @ts-ignore before the problematic line, but like in this case it’d be useless because the error would happen again immediately in the second line.

You can disable this error check globally by opening the tsconfig.json file and setting the noUnusedLocals property to false.

Once you do, restart yarn start in order to pick up the new setting.

There’s also noUnusedParameters to do the same for unused function parameters. Leave it to true now.

One thing I recommend is to do that now that we’re in “building mode”, but then re-enable those checks as soon as your code is starting to finalize, because they can really help make your code better.

Lessons in this unit:

0:	Introduction
1:	Your first TypeScript program
2:	Types
3:	Typing functions
4:	The editor helps you with type errors
5:	Running TypeScript code
6:	Valid types
7:	Type aliases and interfaces
8:	Union types
9:	Typing arrays with generics
10:	The DX of editing TypeScript
11:	There's more...
12:	TypeScript declare a type that can be a string or array of strings
13:	▶︎ TypeScript, disable checks for `declared but its value is never read`
14:	Object destructuring with types in TypeScript
15:	TypeScript Tutorial
16:	Zod: Type-Safe Schema Validation for TypeScript
17:	How I fixed some trouble importing types in .d.ts files