What is core-js?

• It is a polyfill of the JavaScript standard library, which supports:
  • The latest ECMAScript standard.
  • ECMAScript standard library proposals.
  • Some WHATWG / W3C standards (cross-platform or closely related ECMAScript).
• It is maximally modular: you can easily choose to load only the features you will be using.
• It can be used without polluting the global namespace.
• It is tightly integrated with babel: this allows many optimizations of core-js import.