<p>The scope is an important concept that manages the availability of variables. The scope is at the base closures, which defines the idea of global and local variables.</p>
<h2 id="heading-function-scope">Function scope</h2>
<p>JavaScript has function scope: Each function creates a new scope.
Variables defined inside a function are not accessible (visible) from outside the function.
Variables declared with var, let and const are quite similar when declared inside a function.</p>
<h2 id="heading-block-scope">Block Scope</h2>
<p>Before ES6 (2015), JavaScript had only Global Scope and Function Scope.
ES6 introduced two important new JavaScript keywords: let and const.
These two keywords provide Block Scope in JavaScript.
Variables declared inside a { } block cannot be accessed from outside the block:</p>
<p>Example</p>
<pre><code>{
  <span class="hljs-keyword">let</span> x = <span class="hljs-number">2</span>;
}
<span class="hljs-comment">// x can NOT be used here</span>
</code></pre><p>Variables declared with the var keyword can not have block scope.</p>


The scope is an important concept that manages the availability of variables. The scope is at the base closures, which defines the idea of global and local variables.
  

## Function scope

JavaScript has function scope: Each function creates a new scope.
Variables defined inside a function are not accessible (visible) from outside the function.
Variables declared with var, let and const are quite similar when declared inside a function.


## Block Scope

Before ES6 (2015), JavaScript had only Global Scope and Function Scope.
ES6 introduced two important new JavaScript keywords: let and const.
These two keywords provide Block Scope in JavaScript.
Variables declared inside a { } block cannot be accessed from outside the block:

Example
```
{
  let x = 2;
}
// x can NOT be used here
``` 

Variables declared with the var keyword can not have block scope.


TechMan

TechMan

Function scope vs Block scope

Function scope

Block Scope