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Execution Contexts, Hoisting, Scopes, and Closures
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Execution Contexts, Hoisting, Scopes, and Closures

Execution Contexts, Hoisting, Scopes, and Closures are fundamental concepts in JavaScript programming language.
Screenshot from https://ui.dev/ course and it were called “Tyler”
Screenshot from https://ui.dev/ course and it were called “Tyler”
  • Context refers to the this keyword, which is always the first parameter that can be received by a function with the bind method. If it is not received, it will look for it in its parent, until it reaches the window object. If it cannot be found, it will throw an error.
  • Hoisting is the process of declaring a variable before it is used in the code.
  • Scope refers to the range of accessibility of a function or a variable.

Closures

Closures are created when a function is defined inside another function. The inner function creates a closure with its parent function.
When a program starts, the window object is created, along with the this keyword that references the window, and the functions and variables that exist.
When a function is called, a function context is created. Instead of creating the window object, the arguments object is created. If a function or an arrow function is used, a different context is created.
Functions have a scope, and a function inside another function is a closure.
  • Context refers to the this keyword, which is the first parameter that can be received by a function. If it is not received, it will look for it in its parent, until it reaches the window object. If it cannot be found, it will throw an error.
  • Hoisting is the process of declaring a variable before it is used.
  • Scope is the range of accessibility of a function or a variable.
  • Closures occur when a function is created inside another function. The inner function creates a closure with its parent function.
When a program is initiated, the window object is created, along with the this keyword that references the window, and the functions and variables that exist.
When a function is called, a function context is created. Instead of creating the window object, the arguments object is created. If a function or an arrow function is used, a different context is created.
Functions have a scope and a function inside another function is a closure.