I would recommend avoiding adding your own global types if you can avoid it, for example TypeScript has a full type definition for Array.prototype.find [1]. You

I would recommend avoiding adding your own global types if you can avoid it, for example TypeScript has a full type definition for Array.prototype.find [1]. You can enable it without changing the target and breaking things by adding es2015 to lib in your tsconfig compilerOptions [1] https://github.com/Microsoft/TypeScript/blob/5fb39769ada9ff72d905c62069aab136c93f38a8/lib/lib.es2015.core.d.ts#L22-L32 https://github.com/Microsoft/TypeScript/blob/5fb39769ada9ff7...