a simple version of the call() in javascript

myOwnCallSimple.js

/**
 * We could get the parameters with arguments in Javacript. With ES6 spread
 * operator, you could transform it into a real list. Notes: the first
 * parameter is the this object, so we slice it.
 * Problems:
 * 1. we ignore the case the context passed in is primitive type
 * 2. we ignore the case the context passed in is null
 *
 * @param {Object} [context=window]
 * @returns
 */
Function.prototype.myOwnCallBetter = function(context = window) {
  // get the function which calls the call/apply
  context.fn = this;
  let args = [...arguments].slice(1);
  let result = context.fn(...args);
  delete context.fn;
  return result;
};