This is not yet published in DefinitelyTyped. Therefore you've to adapt the installation a little bit. Add following dependency to your package.json:
"dependencies": {
"@types/slate": "git+https://github.com/JanLoebel/types-slate.git"
},
Run npm install and that's it.
This package contains type definitions for Slate (https://github.com/ianstormtaylor/slate).
Please feel free to contribute!
These definitions were written by Andy Kent https://github.com/andykent, Jamie Talbot https://github.com/majelbstoat, Jan Löbel https://github.com/JanLoebel.