1 Scope (
global scope)objects that can be accessed anywhere in your code have global scope, and in general there are several scenarios where you have global scope:(1) The outermost function and the variables defined outside the outermost function have global scope. (2) All variables that do not have a direct assignment defined are automatically declared as having global scope. (3) All Window object properties have global scope 2 scope (
local scope)In contrast to global scopes, local scopes are generally accessible only within a fixed code fragment, the most common of which is inside a function, and in some places it is also seen that this scope is called a function scope. 3. Scope
chain (scope Chain)when a function is created, it fills a global object in its scope chain, which contains all global variables.
JS Scope, scope chain
