Determining the presence of cyclic dependencies in a file graph

Implement the function hasCircularDependency that checks whether there is a cycle in the dependency graph between files.

type Resource = string;
type Vector = Record<Resource, Resource[]>;

function hasCircularDependency(entrypoint: Resource, deps: Vector): boolean {
  // your code here
}

// example
console.warn(hasCircularDependency('index.js', {
  'index.js': ['foo.js', 'bar.js'],
  'bar.js': ['baz.js'],
  'foo.js': ['baz.js'],
  'baz.js': ['x.js'],
  'x.js': ['foo.js'] // cycle: index → foo → baz → x → foo
})); // true