Both scenario, the typeof the variable will be “undefined”.
But undeclared variable will raise a exception.
Is there a easy way to handle this?
Both scenario, the typeof the variable will be undefined. But undeclared variable will raise
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Both scenario, the typeof the variable will be “undefined”.
But undeclared variable will raise a exception.
Is there a easy way to handle this?
You may find the question (and my answer) in How to check if a variable or object is undefined? relevant. In general, I view any access to an “undeclared variable” a programming error.
However, this particular case can *only** be detected with the use of detecting for a
ReferenceErrorexception. But, yuck, yuck, yuck! Remember variable declarations are a static lexical construct, ignoring the quirks with property-variables of the global object.ReferenceError, and now “strict”, exist for a reason and I suspect this is an X-Y problem. I do not even recommend the use oftypeoffor this purpose: fix the code 🙂Happy coding.
*It has been pointed out that
"variable" in windowwill also [and only] work for global “variables” (they are really just properties that don’t need be qualified in all contexts).