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{"@context":"https://schema.org","@type":"FAQPage","mainEntity":[{"@type":"Question","name":"What is variable scope in JavaScript?","acceptedAnswer":{"@type":"Answer","text":"Variable scope determines where in your code a variable can be accessed. JavaScript has three types of scope: global scope (accessible everywhere), function/local scope (accessible only within a function), and block scope (accessible only within a block like if/for statements, applies to let and const)."}},{"@type":"Question","name":"What is the difference between global and local scope?","acceptedAnswer":{"@type":"Answer","text":"Global scope variables are declared outside any function and can be accessed from anywhere in your code. Local scope variables are declared inside a function and can only be accessed within that function. Local variables are created when the function starts and deleted when the function completes."}},{"@type":"Question","name":"What is block scope in JavaScript?","acceptedAnswer":{"@type":"Answer","text":"Block scope was introduced in ES6 with let and const. Variables declared with let or const inside a block (code between curly braces {}) are only accessible within that block. This includes if statements, for loops, and while loops. Variables declared with var ignore block scope and are function-scoped instead."}},{"@type":"Question","name":"What is the scope chain in JavaScript?","acceptedAnswer":{"@type":"Answer","text":"The scope chain is the order in which JavaScript looks for variables. When a variable is used, JavaScript first looks in the current scope, then in the outer scope, and continues up to the global scope. This chain of scopes is determined by where functions are defined (lexical scoping), not where they are called."}},{"@type":"Question","name":"How does var differ from let and const in terms of scope?","acceptedAnswer":{"@type":"Answer","text":"var is function-scoped, meaning it is accessible throughout the entire function where it is declared, ignoring block boundaries. let and const are block-scoped, meaning they are only accessible within the block where they are declared. This makes let and const more predictable and helps prevent accidental variable leakage."}}]}