![]() In JavaScript, a ReferenceError is thrown when trying to access a previously undeclared variable. log (variable ) // Output: ReferenceError: variable is not defined In JavaScript, an undeclared variable is assigned the value undefined at execution and is also of type undefined. This brings us to our first point of note: log ( typeof variable ) // Output: undefined If you’ve ever wondered why you were able to call functions before you wrote them in your code, then read on! undefined vs ReferenceErrorīefore we begin in earnest, let’s deliberate on a few things. ![]() Of note however, is the fact that the hoisting mechanism only moves the declaration. Inevitably, this means that no matter where functions and variables are declared, they are moved to the top of their scope regardless of whether their scope is global or local. Hoisting is a JavaScript mechanism where variables and function declarations are moved to the top of their scope before code execution. Before we dive in, let’s get to grips with what hoisting is. In this tutorial, we’ll investigate how the famed hoisting mechanism occurs in JavaScript.
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