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JavaScript Hoisting in Functions and Variables
- JavaScript goes through a preparation phase before executing the code, which involves hoisting variables and function declarations.
- During the setup phase, JavaScript registers declarations like var, let, const, function declarations, and class declarations in memory.
- Function declarations are fully loaded into memory during the setup phase, allowing them to be called before their appearance in the code.
- Function expressions, on the other hand, are not hoisted and must be assigned before they can be called.
- Variables declared with var are hoisted with an initial value of undefined, while let and const variables are hoisted but left uninitialized.
- Accessing let and const variables before their declaration results in a ReferenceError due to the temporal dead zone.
- Class declarations follow a similar hoisting behavior to let and const variables, being hoisted but not accessible until their respective declarations.
- Hoisting also applies within function and block scopes, where declarations are moved to the top of their scope before execution.
- Repeating function declarations in the same scope results in the last declared function taking precedence during execution.
- Understanding JavaScript hoisting involves recognizing the separation between the setup phase, where names are registered, and the execution phase, where actual values are assigned and logic begins.
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