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15 lines
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15 lines
1.3 KiB
# Scopes |
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In JavaScript, scope refers to the visibility of a variable or how it can be used after it is declared. The scope of a variable depends on the keyword that was used to declare it. |
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The three types of Scope are Global Scope, Function Scope, and Block Scope. Before ES6 (2015), JavaScript had only Global Scope and Function Scope with the `var` keyword. ES6 introduced `let` and `const` which allow Block Scope in JavaScript. |
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Global Scope: Variables declared outside any function or curly braces '{}' have Global Scope, and can be accessed from anywhere within the same Javascript code. `var`, `let` and `const` all provide this Scope. |
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Function Scope: Variables declared within a function can only be used within that same function. Outside that function, they are undefined. `var`, `let` and `const` all provide this Scope. |
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Block Scope: A block is any part of JavaScript code bounded by '{}'. Variables declared within a block can not be accessed outside that block. This Scope is only provided by the `let` and `const` keywords. If you declare a variable within a block using the `var` keyword, it will NOT have Block Scope. |
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<ResourceGroupTitle>Free Content</ResourceGroupTitle> |
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<BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.w3schools.com/js/js_scope.asp'>JavaScript Scope</BadgeLink>
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