Returns a flag indicating whether a key has an item associated with it in the Dictionary
|JScript - 3.0|
|Internet Explorer - 4.0|
|Property/method value type:||Boolean primitive|
|Argument list:||aKey||A textual key name|
Dictionaries are a useful way to collect items together at random intervals. The Dictionary can then be tested later on after the items have been added. This method provides a way to test whether a specific name-value pair has been added to the Dictionary.