Javascript has a convenient way to check if a class (or any other) exists in the global scope:

typeof SomeUndeclaredOne === 'undefined'

This method doesn't work in typescript because it produces a compilation error:

error TS2304: Cannot find name 'SomeUndeclaredOne'

So my question is: what is the easiest way to check if a class exists in a typescript? I'm looking for a generic way that works not only in browsers but also other environments (e.g. node.js or other environments that don't have a global object) and works with popular module systems (like ESModules, CommonJS) too.

Thanks in advance for any advice.

CodePudding user response：

You could declare the class with TypeScript to get rid of the error.

declare class SomeUndeclaredOne {}
console.log(typeof SomeUndeclaredOne === "undefined")