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Practice

Variable Declaration Keyword - let

let is a keyword used in JavaScript to declare variables.

Similar to var, it creates variables that store data and can be reassigned. However, variables declared with let have block-level scope.

Block-level scope means that the variable is accessible only within the block of code enclosed by curly braces.

For instance, if we replace var with let in the example code from the previous lesson, it would look like this:

let Variable Declaration
if (true) {
    let name = "one";
}

console.log(name); // ReferenceError: name is not defined

In the code above, the name variable declared with let is accessible only within the if block.

Trying to access the name variable outside the conditional statement block composed of if will result in a ReferenceError.

As such, variables declared with let possess block-level scope, meaning they can only be accessed within the block.


Reassignable let Variables​

A variable declared with let can be reassigned to a different value after its initial declaration.

Variable Reassignment
let number = 10;
number = 20; // The value of the variable number is changed to 20

console.log(number); // 20

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