contents: fix behavior for typeof for undeclared variables
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The `typeof` operator returns `"undefined"` when used with an undeclared variable, `console.log(typeof z) // "undefined"`. However, directly accessing an undeclared variable (e.g., `console.log(z)`) throws a `ReferenceError`. This distinction is important for understanding JavaScript's behavior with undeclared variables and typeof. Reference [Mdn](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/typeof?#interaction_with_undeclared_and_uninitialized_variables)
yangshun
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ReferenceError --> undefinedtypeof for undeclared variables
yangshun
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Jan 8, 2025
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yangshun
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Great catch, thanks so much @MaryRichelle
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The
typeofoperator returns"undefined"when used with an undeclared variable,console.log(typeof z) // "undefined".However, directly accessing an undeclared variable (e.g.,
console.log(z)) throws aReferenceError. This distinction is important for understanding JavaScript's behavior with undeclared variables and typeof.Reference Mdn