Get the original function in javascript. useful if someone has replaced the function or you must guarantee that it is clean.

Original_Function.js

function _Function(path) {
    let fn = () => {};
    const split = path.split('.');

    const $iframe = document.createElement('iframe');
    $iframe.src = 'about:blank';
    document.body.appendChild($iframe);

    fn = $iframe.contentWindow;
    for (let i=0; i<split.length; i++) {
      fn = fn[split[i]];
    }

    $iframe.parentElement.removeChild($iframe);

    return fn;
  }