Boolean Expressions

• false
• 0 (zero)
• 0.0 (zero)
• "" (empty string)
• undefined
• NaN (not a number)
  

• true
• 1
• "false"
• "0"
  
• object (any object)

• For files created for Flash Player 6 and earlier, a string only evaluates to true if it represents a non-zero number.