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Mastering JavaScript by Ved Antani

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Scoping

For beginners, JavaScript scoping is slightly confusing. These concepts may seem straightforward; however, they are not. Some important subtleties exist that must be understood in order to master the concept. So what is Scope? In JavaScript, scope refers to the current context of code.

A variable's scope is the context in which the variable exists. The scope specifies from where you can access a variable and whether you have access to the variable in that context. Scopes can be globally or locally defined.

Global scope

Any variable that you declare is by default defined in global scope. This is one of the most annoying language design decisions taken in JavaScript. As a global variable is visible in all other scopes, a global variable can ...

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