You can treat all variables as boolean values... that is, you can say:
if (myVariable)
...no matter what data type is actually in the variable. Here's how they're all treated.
Undefined:
Always equates to FALSE..
Numbers:
Equates to FALSE if it contains the value 0; TRUE for everything else.
Strings:
Always equates to TRUE.
File handles:
Always equates to TRUE.
Object types:
Always equates to TRUE.
Stacks:
Equates to FALSE if the stack is empty; TRUE for everything else.
Function handles:
Always equates to TRUE.
Animations:
Always equates to TRUE.
Costumes:
Always equates to TRUE.
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