Shulou(Shulou.com)06/02 Report--

Editor to share with you what the scope of JavaScript, I believe that 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!

I. scope

Generally speaking, the name used in a piece of program code is not always valid and available, and the scope of the code that limits the availability of the name is the scope of the name. The use of scope improves the locality of program logic, enhances the reliability of the program, and reduces name conflicts.

There are two scopes in JavaScript (before es6):

Global scope

Local scope (function scope)

After ES6, there is also a block-level scope, which will be detailed later.

1. Global scope

The environment that acts on all code execution (inside the entire script tag) or a separate js file.

2. Local scope

The code environment that acts within the function is the local scope. It is also called function scope because it has something to do with the function.

For example:

For (let iTuno Bandi)

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.