en.javascript.info/1-js/06-advanced-functions/09-call-apply-decorators/02-delay/solution.md

The solution:

function delay(f, ms) {

  return function() {
    setTimeout(() => f.apply(this, arguments), ms);
  };

}

Please note how an arrow function is used here. As we know, arrow functions do not have own this and arguments, so f.apply(this, arguments) takes this and arguments from the wrapper.

If we pass a regular function, setTimeout would call it without arguments and this=window (in-browser), so we'd need to write a bit more code to pass them from the wrapper:

function delay(f, ms) {

  // added variables to pass this and arguments from the wrapper inside setTimeout
  return function(...args) {
    let savedThis = this;
    setTimeout(function() {
      f.apply(savedThis, args);
    }, ms);
  };

}