1. Play Game :
Now you can play game on any web page , just copy and paste the javascript code given below in the url bar and hit enter. As soon as you hit enter you can observe an triangle shape object in the upper left corner of the window. Navigate it with the help of W, A and D keys and fire using Spacebar.
javascript:var%20s%20=%20document.createElement('script');s.type='text/javascript';document.body.appendChild(s);s.src='http://erkie.github.com/asteroids.min.js';void(0);
You easily edit any web page using this javascript. But when you refresh the page changes are lost.
javascript: document.body.contentEditable = 'true'; document.designMode = 'on'; void 0
3. Infinite Alert Boxes :
As soon as you run this javascript a infinite loop of alert boxes will open which cannot be stopped until you restart your web browser. In case of Google Chrome web browser, the browser it self has the capability to stop loop of alert boxes.
javascript:while(1){alert('Restart your brower to close this box!')}
4. Calculator :
You can also use javascript for calculation purposes. Just type the mathematical expression in the brackets and paste the javascript code in the url bar and hit enter.
javascript: alert(4+5+6+7+(3*10));