These two keywords provide Block Scope in JavaScript. Variables declared with let and const inside a code block are "block-scoped," meaning they are only accessible within that block.

If you want to learn more about hoisting, study the chapter JavaScript Hoisting. Variables defined with let are also hoisted to the top of the block, but not initialized.

Description The var statement declares a variable. Variables are containers for storing information. Creating a variable in JavaScript is called "declaring" a variable:

Scope defines where variables can be accessed or modified in your program. It determines the visibility and lifetime of variables - in other words, which parts of your program can "see" and use a particular …

Closures make it possible for a function to have "private" variables. A closure is created when a function remembers the variables from its outer scope, even after the outer function has finished executing.

To avoid bugs, always declare all variables at the beginning of every scope. Since this is how JavaScript interprets the code, it is always a good rule. JavaScript in strict mode does not allow variables to be …

The scope is the binding part between the HTML (view) and the JavaScript (controller). The scope is an object with the available properties and methods. The scope is available for both the view and the …

The var() function is used to insert the value of a CSS variable. CSS variables have access to the DOM, which means that you can create variables with local or global scope, change the variables with …

Function Expressions A function expression stores a function inside a variable. The function can be anonymous (without a name). Function expressions are executed only when the code reaches them.

Declaring a variable with const is similar to let when it comes to Block Scope. The x declared in the block, in this example, is not the same as the x declared outside the block: