In-depth understanding of the scope of JavaScript

Every person who has written a program will not be unfamiliar with the concept of scope. In this article, let's talk about the definition Cr.

Every person who has written a program will not be unfamiliar with the concept of scope. In this article, let's talk about the scope of Javascript.

In Javascript, the global environment itself is an object. In the browser host, this object is a window, and when Javascript is used for other non-browser hosts, such as embedded environments, it may be other objects.

I have also corrected this idea. Many people think that Javascript is only used in browsers. In fact, Javascript can also be used in many non-Web scenarios, according to the introduction, Javascript has performed well in some embedded-based application fields. Of course, I have only heard of the legends.

To put it bluntly, when we write down: var I = 1, we actually declare a variable in the window scope.

When I = 1 is written, the attribute of a window is declared.

See the following code: