When a new function scope is declared, the variables in the surrounding context are made available to it. This is a simple idea—don’t let the fancy name fool you.

A function scope is in a way also a block scope, so let and const would behave the same way they did in our previous examples. However, function scopes also encapsulate variables declared with var.

Pre-standard C++ had quirky scope behavior similar to your first example - variables declared specifically in a for loop's initializer statement remained in scope through the end of the block.

Blocks As Scopes","","Block-scope refers to the idea that variables and functions can belong to an arbitrary block of code, rather than an enclosing function.","","Starting with ES3, the `try/catch` ...

In the case of function declarations (e.g. function doStuff () { … }), the [ [Scope]] property is assigned to the declaring context’s VariableEnvironment. We’ll discuss the reasons for this disparity ...

The “i” var in the “doSomething” function is assigned the value returned by the immediate function. The “x” var is scoped to the immediate function giving us block-like scope for our variables. Of ...