When I create a TypeScript React app with create-react-app app-name --template typescript and try to edit it in VSCode, I get the following error message
Cannot use JSX unless the '--jsx' flag is provided. ts(17004)
error.
I found out that since version 17 of React, react-jsx is used for the jsx option in TypeScript, but the version of TypeScript that can be used for this option is 4.1 or higher, and VSCode's TypeScript version is older than that of React. The error occurred because the TypeScript version of VSCode was too old.
I am sure that the error will be resolved when VSCode's TypeScript version is eventually upgraded, but I decided to deal with it by upgrading the local TypeScript version as soon as possible.
VSCode's TypeScript version changes were referenced below.
The current TypeScript version of VSCode is 4.0.3.
Install TypeScript in the root folder of the workspace.
npm init
npm install --save-dev typescript
From the VSCode command palette, select and change the TypeScript version to be used in Ctrl+Shift+p and typescript select.
The error was successfully resolved.
Impressions, etc.
I mistakenly thought that the TypeScript version of VSCode was changed dynamically by looking at the folder where the files are located.
