Add content on 'scope and function stack' (#2165)

adding content of the scope and function stack node in Javascript roadmap.

content/roadmaps/106-javascript/content/109-javascript-functions/105-scope-and-function-stack/readme.md

@@ -1 +1,17 @@
-# Scope and function stack
+# Scope and function stack
+
+## Scope
+A space or environment in which a particular variable or function can be accessed or used. Accessibility of this variable or function depends on where it is defined.
+
+JavaScript has the following kinds of scopes:
+- **Global scope**: The default scope for all code running in script mode.
+- **Module scope**: The scope for code running in module mode.
+- **Function scope**: The scope created with a function.
+- **Block scope**: The scope created with a pair of curly braces (a block).
+
+## Function Stack (Call stack)
+The function stack is how the interpreter keeps track of its place in a script that calls multiple functions, like which function is currently executing and which functions  within that function are being called.
+
+<ResourceGroupTitle>Free Content</ResourceGroupTitle>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://developer.mozilla.org/en-US/docs/Glossary/Call_stack'>Function stack (call stack) - MDN</BadgeLink>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://developer.mozilla.org/en-US/docs/Glossary/Scope'>Kinds of Scope - MDN</BadgeLink>