Lexical Environment in JS

Lexical Environment of a variable = where it sits physically in the code ( i.e. inside a function or within global context, or within some if statement or for loop etc. or a code scope created by wrapping the code inside a pair of curly brackets {..} )

Lexical Environment is created every time you create a scope using the curly brackets {}. It can be nested: {{…}}

Global scope

Javascript runtime = software that executes our javascript code.

JS Runtime, whenever it starts running a javascript program, would first create a 'Global' scope for the program and then keep on creating child scopes or grand child scopes etc. as and when it concounters a pair of curly brackets {..}.

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