const. Each method has its own quirks, but the most commonly used are
var are function-scoped, meaning they are accessible within the entire function they are declared in.
Here's an example:
Because of these quirks, it's generally recommended to use
var, variables declared with
let are block-scoped, which means they are only accessible within the block they are declared in. This can help prevent accidental manipulation of variables outside of their intended scope.
Here's an example using
let doesn't suffer from hoisting issues:
const is block-scoped, but with one key difference: variables declared with
const cannot be reassigned. This makes
const great for declaring constant values or variables that should remain unchanged throughout the execution of your code.
An example with
Manipulating Data with Variables
Updating Variable Values
You can update the value of a variable using the assignment operator (
=) and any relevant operation:
var is the old way of declaring variables, while
const were introduced in ES6 (ECMAScript 2015). Here's an example of declaring variables with each keyword:
What is the difference between `let` and `const`?
let allows you to change the value of the variable later in your code, while
const creates a constant variable, which means its value cannot be changed once it's assigned. Here's a comparison:
How do I assign a value to a variable?
=. This is called the assignment operator. For example:
Can a variable hold different types of values?