tslib best that works with typescript 3.8.3 code example
Example: add module tslib
// TypeScript 3.9.2 or later
npm install tslib
// TypeScript 3.8.4 or earlier
npm install tslib@^1
// TypeScript 2.3.2 or earlier
npm install tslib@1.6.1// TypeScript 3.9.2 or later
npm install tslib
// TypeScript 3.8.4 or earlier
npm install tslib@^1
// TypeScript 2.3.2 or earlier
npm install tslib@1.6.1