Learning ActionScript 2.0 in Adobe Flash
Best Practices and Coding Conventions for ActionScript 2.0 > ActionScript and Flash Player optimization > Optimizing your code

Optimizing your code

Remember the following guidelines when you optimize your code:

• Avoid calling a function multiple times from within a loop.

  It is better to include the contents of a small function inside the loop.

• Use native functions when possible. 

  Native functions are faster than user-defined functions.

• Don't overuse the Object type.  

  Data-type annotations should be precise, because it improves performance. Use the Object type only when there is no reasonable alternative.

• Avoid using the eval() function or array access operator.

  Often, setting the local reference once is preferable and more efficient.

• Assign the Array.length to a variable before a loop.

  Assign Array.length to a variable before a loop to use as its condition, rather than using myArr.length itself. For example,

  var fontArr:Array = TextField.getFontList();
  var arrayLen:Number = fontArr.length;
  for (var i:Number = 0; i < arrayLen; i++) {
      trace(fontArr[i]);
  }
  

  instead of:

  var fontArr:Array = TextField.getFontList();
  for (var i:Number = 0; i < fontArr.length; i++) {
      trace(fontArr[i]);
  }
  

• Focus on optimizing loops, and any repeating actions.

  Flash Player spends a lot of time processing loops (such as those that use the setInterval() function).

• Add the var keyword when declaring a variable.
• Don't use class variables or global variables when local variables will suffice.

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