Chapter 14. Lexical Structure

14.1. Whitespace

varx   // Oops! No whitespace between the keyword var and the variable x.
var x  // That's better...because of the whitespace the interpreter
       // can now read our code.

Whitespace is optional when there is some other delimiter (separator) that tells ActionScript where one token ends and another begins. The following code is quite legitimate because the operators =, +, and / separate x, 10, 5, and y from one another:

x=10+5/y;        // Crowded, but legitimate
x = 10 + 5 / y;  // Easier to read, but the same as above

Similarly, whitespace is optional when there are other characters such as square brackets, parentheses, curly braces, commas, and greater-than or less-than signs to act as delimiters. These are all perfectly legal if somewhat claustrophobic:

for(var i=0;i<10;i++){trace(i);}
if(x==7){y=[1,2,3,4,5,6,7,8,9,10];}
myMeth=function(arg1,arg2,arg3){trace(arg1+arg2+arg3);};

Extra whitespace is simply a matter of style, because it is ignored by the ActionScript interpreter. That said, there are conventions you should follow to make your code more readable. For example, the following is another legitimate way to rewrite the earlier assignment expression, but it is obviously harder to read:

x =
  10
  + 5
  / y;

Notice that the statement is terminated by the semicolon not the line breaks. In nearly all cases, line breaks are inconsequential and do not act as statement terminators. Hence, we often use one or more line breaks (in concert with spaces or tabs) to make complex statements easier to read:

myNestedArray = [[x, y, z],
                [1, 2, 3],
                ["joshua davis", "yugo nakamura", "james patterson"]];
// Much nicer than:
myNestedArray = [[x, y, z], [1, 2, 3],["joshua davis","yugo nakamura",
"james patterson"]];
// And also nicer than:
myNestedArray = [[x, y, z],
[1, 2, 3],
["joshua davis","yugo nakamura","james patterson"]];

Note that whitespace within the quotes that delimit a string is relevant whereas whitespace outside the quotes is ignored. Compare these two examples:

x = 5;
trace("The value of x is"  +   x);   // Displays: "The value of x is5"
trace("The value of x is "+x);       // Displays: "The value of x is 5"