What is lexical scope in javascript?

A scope in programming refers to the area in which a variable or function is visible.There are two types of scope we know,

• Global Scope
• Local Scope

The term "Lexical scope" refers to the ability of a function to access the variables inside and outside of that function. Simply saying, that a variable defined outside a function can be accessed by another function defined after the variable declaration. On the other hand, variables defined inside a function are not accessible outside of it.
 

var x = 5; // available to all functions

var parent = function (){ // parent function
    var y = 10;

    var child = function (){ // child function
        var z = 30;

    }
    return;
}

• In the above code variable "z" accessed only inside "child" function whereas variable "y" can be accessed by "child" and "parent" function.
• Variable "x" available for all the functions inside and outside of parent function.