Creating and Categorizing Data
There are two ways to create a new datum with ActionScript, both methods requiring the use of expressions—phrases of code that represent data in our scripts.
A literal expression (or literal for short) is a series of letters, numbers, and punctuation that is the datum. A data literal is a verbatim description of data in a program’s source code. This contrasts with a variable, which is a container that merely holds a datum. Each datatype defines its own rules for the creation of literals. Here are some examples of literals:
"loading...please wait" // A string literal 1.51 // A numeric literal ["jane", "jonathan"] // An array literal
Note that movie clips cannot be represented by literals, but are referred to by instance names.
We can also generate data programmatically with a complex expression. Complex expressions represent data as a phrase of code with a value that must be calculated or computed, not taken literally. The calculated value is the datum being represented. For example, each of these complex expressions results in a single datum:
1999 + 1 // Yields the datum 2000 "hi " + "ma!" // Yields the datum "hi ma!" firstName // Yields the value of the variable
firstName_currentframe // Yields the frame number of the playhead's current position new Date( ) // Yields a new
Dateobject with the current date and time
Notice that an individual literal expression like 1999 or 1 can be a valid part of a larger complex expression, as in 1999 + 1.