+1  A: 

In this example:

testCall: function()

testCall is now a function available on the object you're in, like this: object.testCall() It can access other functions, properties, etc inside this object if it needs to.

In this version:

function testCall()

testCall is just a globally available method, not scoped to the object or plugin, whatever you're dealing with, you can call it from anywhere, like this: testCall()

Nick Craver
+2  A: 
Pointy
A: 
T.J. Crowder