Case Analysis of JavaScript Global scope and function scope

This article introduces the relevant knowledge of "JavaScript global scope and function scope instance analysis". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Before ES2015, JavaScript had only two types of scope: global scope and function scope

Global scope

Variables declared globally (outside the function) have global scope.

Example

Var carName = "porsche"

/ / the code here can use carName

Function myFunction () {

/ / the code here can also use carName

}

Global variables can be accessed anywhere in the JavaScript program.

Function scope

Variables declared locally (within a function) have function scope.

Example

/ / the code here cannot use carName

Function myFunction () {

Var carName = "porsche"

/ / code here CAN use carName

}

/ / the code here cannot use carName

Local variables can only be accessed within the function in which they are declared.

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