Learn JavaScript Scope Cheatsheet PDF
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Uploaded by WellBehavedSardonyx1186
Kebbi State University of Science and Technology
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Summary
This document explains JavaScript scope concepts, encompassing global scope, function scope, and block scope. It further discusses block-scoped variables using 'const' and 'let,' highlighting their accessibility within specific code blocks. Global variables, declared outside functions or blocks, are accessible throughout the program.
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Cheatsheets / Learn JavaScript Scope Scope Scope is a concept that refers to where values and function myFunction() { functions can be accessed. Various scopes include: Global scope (a value/function in the global var pizzaName = "Volvo"; scope can be used...
Cheatsheets / Learn JavaScript Scope Scope Scope is a concept that refers to where values and function myFunction() { functions can be accessed. Various scopes include: Global scope (a value/function in the global var pizzaName = "Volvo"; scope can be used anywhere in the entire // Code here can use pizzaName program) File or module scope (the value/function can only be accessed from within the file) } Function scope (only visible within the function), Code block scope (only visible within a {... // Code here can't use pizzaName } codeblock) Block Scoped Variables const and let are block scoped variables, meaning const isLoggedIn = true; they are only accessible in their block or nested blocks. In the given code block, trying to print the statusMessage using the console.log() if (isLoggedIn == true) { method will result in a ReferenceError. It is const statusMessage = 'User is logged accessible only inside that if block. in.'; } console.log(statusMessage); // Uncaught ReferenceError: statusMessage is not defined Global Variables JavaScript variables that are declared outside of blocks // Variable declared globally or functions can exist in the global scope, which means const color = 'blue'; they are accessible throughout a program. Variables declared outside of smaller block or function scopes are accessible inside those smaller scopes. function printColor() { Note: It is best practice to keep global variables to a console.log(color); minimum. } printColor(); // Prints: blue Print Share
