How to declare global variable in javascript

In javascript global variable can be declared by

• declared outside the function 
• declared with the window object

and it can be accessed from anywhere from the code

Example "1"

window.value='Qandeel';// by window object  

function a(){  
alert(value);  
} 
a();

Example "2"

var value=50;//global scope

function a(){  
alert(value);  
} 
a();