npm install --save @types/core-js
This package contains type definitions for core-js ( https://github.com/zloirock/core-js/ ).
Files were exported from https://github.com/DefinitelyTyped/DefinitelyTyped/tree/master/types/core-js
Additional Details
These definitions were written by Ron Buckton https://github.com/rbuckton, Michel Felipe https://github.com/mfdeveloper.