How to realize the local and global scope of JavaScript

This article mainly introduces the relevant knowledge of "how to realize the local and global scope of JavaScript". The editor shows you the operation process through an actual case. The operation method is simple, fast and practical. I hope this article "how to realize the local and global scope of JavaScript" can help you solve the problem.

Scope refers to the collection of variables that you have access to.

JavaScript function scope

There are two scope types in JavaScript:

Global scope

JavaScript has a function scope: each function creates a new scope.

The scope determines the accessibility (visibility) of these variables.

Variables defined within a function are inaccessible (invisible) from outside the function.

Local JavaScript variable

Variables declared in the JavaScript function become local variables of the function.

The scope of local variables is local: they can only be accessed within the function.

Example

/ / the code here cannot use the carName variable

Function myFunction () {

Var carName = "porsche"

/ / the code here can use the carName variable

}

Because you can only recognize local variables within a function, you can use variables of the same name in different functions.

Local variables are created at the beginning of the function and deleted when the function is completed.

Global JavaScript variable

Variables declared outside the function become global variables.

The scope of a global variable is global: it can be accessed by all scripts and functions of a web page.

Example

Var carName = "porsche"

/ / the code here can use the carName variable

Function myFunction () {

/ / the code here can also use the carName variable

}

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