A constant is just like a variable, but it must be given a value when it is declared (created), and that value can never change. In other words, a constant always contains the same information.

To declare (create) a constant, we use the keyword const.

const earthRadiusKm = 6371;

Assigning a new value to the constant will cause an error, we can not do: earthRadiusKm = 6400;

The name of constants can also be used to represent the information they contain, in the same way as variables.

Tip:

Don’t forget to comment out alerts if you don’t want them to pop-up every time.

Challenge:

Create a constant, and display it an alert pop-up box.

Answer const dogLegs = 4;
alert(dogLegs)
Challenge:

Try to assign a new value to your constant to see what happens.

Answer const dogLegs = 4;
dogLegs = 3;
alert(dogLegs)
Go to Step 8