What is the scope of js variables

Editor to share with you what the scope of js variables are, I believe most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

1. The scope of variables is mainly divided into global scope, local scope and block scope.

The corresponding variables are global variables (declared outside all functions), local variables (variables declared in the function body or named parameters of the function), and block-level variables (declared in blocks are only valid in blocks).

2. The variable scope declared by var has global scope and function scope, and there is no block scope. Both const and let have it.

Example

Var v1 = "a"; let v2 = "b";; scopeTest (); function scopeTest () {var v1 = "aa"; let v2 = "bb"; if (true) {let v1 = "aaa"; console.log ("intra-block output v1 =" + v1);} console.log ("function body output v1 =" + v1) Console.log ("function body output v2 =" + v2);} console.log ("function external output v1 =" + v1); console.log ("function external output v1 =" + v2); these are all the contents of the article "what is the scope of js variables?" Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!