4.0.0

Breaking Changes

• Use PromiseLike instead of Promise in TypeScript (#40)

  This is only a breaking change for TypeScript users.

  In the following code:

  function foo(x: PromiseLike<string> | string) {
    if (isPromise(x)) {
      return x;
    } else {
      return Promise.resolve(x);
    }
  }

  TypeScript would previously have incorrectly inferred foo as returning Promisestring>when in fact it returnsPromiseLikestring>. The latest version fixes this. If you instead had the following code, it should work exactly the same as before:

  function foo(x: Promise<string> | string) {
    if (isPromise(x)) {
      return x;
    } else {
      return Promise.resolve(x);
    }
  }

  This update is to reflect the fact that is-promise does "duck" typing, rather than an instanceof check.