Lexical Environment

Lexical environments contain an environment record in which the variables are stored and a reference to their parent environment.

Lexical environments build a tree structure.

function b(){
  function a(){
   return 0;
 }
return 0;
}

• In this case function a is lexically inside the b function.

In JavaScript, without this keyword, lexical scope is important where data and variable is defined.

• Dynamic scope: where the function is called.