PHP's realpath in JavaScript

module.exports = functionrealpath (path) {
//  discuss at: https://locutus.io/php/realpath/
// original by: mk.keck
// improved by: Kevin van Zonneveld (https://kvz.io)
//      note 1: Returned path is an url like e.g. 'https://yourhost.tld/path/'
//   example 1: realpath('some/dir/.././_supporters/pj_test_supportfile_1.htm')
//   returns 1: 'some/_supporters/pj_test_supportfile_1.htm'
if (typeofwindow === 'undefined') {
const nodePath = require('path')
return nodePath.normalize(path)
  }
let p = 0
let arr = [] // Save the root, if not given
const r = this.window.location.href // Avoid input failures
// Check if there's a port in path (like 'https://')
  path = (path + '').replace('\\', '/')
if (path.indexOf('://') !== -1) {
    p = 1
  }
// Ok, there's not a port in path, so let's take the root
if (!p) {
    path = r.substring(0, r.lastIndexOf('/') + 1) + path
  }
// Explode the given path into it's parts
  arr = path.split('/') // The path is an array now
  path = [] // Foreach part make a check
for (const k in arr) { // This is'nt really interesting
if (arr[k] === '.') {
continue
    }
// This reduces the realpath
if (arr[k] === '..') {
/* But only if there more than 3 parts in the path-array.
       * The first three parts are for the uri */
if (path.length > 3) {
        path.pop()
      }
    } else {
// This adds parts to the realpath
// But only if the part is not empty or the uri
// (the first three parts ar needed) was not
// saved
if ((path.length < 2) || (arr[k] !== '')) {
        path.push(arr[k])
      }
    }
  }
// Returns the absloute path as a string
return path.join('/')
}