Internet Explorer 11 appends the "zx=" parameter to the URL

Issue

• DXP administrators and users may notice a zx= parameter appended to the URL while navigating through the pages of the portal. For example: http://localhost:8080/web/guest/page2?zx=5ml8zs91pgxm

Environment

• Liferay DXP 7.0+

Resolution

• The current behavior is expected on IE11: the zx parameter is added by the Automatic Single Page Applications (going forward: SPA) to make the URL unique and prevent caching.
  
  
• While disabling the SPA globally in the portal through javascript.single.page.application.enabled=false in portal-ext.properties would be a possible workaround, we don't recommend this strategy as it may affect the general page loading performance.
  
  
• A better approach would be disabling the SPA on IE11 only: this can be done as follows:
  
  
  • • Liferay DXP 7.3, DXP 7.2 and DXP 7.1: Control Panel > Configuration > System Settings > Platform > Infrastructure > Frontend SPA Infrastructure
    • Liferay 7.0 DXP: Control Panel > Configuration > System Settings > Foundation > Frontend SPA Infrastructure

The change won't affect other browsers and will also mitigate a known performance issue with IE11 and SPA: Internet Explorer 11 Memory Leaks.

• Alternatively, you may use the new MS Chromium Edge (e.g. Edge version 87.0.664.75), where this behavior is not present.

Additional Information

• Internet-Explorer-Support-Policy
  
  
• On IE11, when the httpMethod is GET, the senna.js / metal-uri adds the zx parameter to the end of the URL to make the URI unique to avoid caching. At https://github.com/liferay/senna.js/blob/master/src/screen/RequestScreen.js#L120-L122:
  

  formatLoadPath(path) {
   var uri = new Uri(path);
  uri.setHostname(globals.window.location.hostname);
   uri.setProtocol(globals.window.location.protocol);
  if (globals.window.location.port) { 
     uri.setPort(globals.window.location.port); 
  }
  if (utils.isIeOrEdge() && this.httpMethod === RequestScreen.GET) { 
    return uri.makeUnique().toString(); 
  }
  return uri.toString();
  }

  Below, the makeUnique function within the metal-uri package at https://github.com/metal/metal-plugins/blob/master/packages/metal-uri/src/Uri.js#L274-L277:
  

  makeUnique() { 
      this.setParameterValue(Uri.RANDOM_PARAM, string.getRandomString()); 
      return this;
   }

  At https://github.com/metal/metal-plugins/blob/master/packages/metal-uri/src/Uri.js#L498, the Uri.RANDOM_PARAM value will then be zx:
  

  Uri.RANDOM_PARAM = 'zx';