Using of variables

In order to use a variable, you should first declare it: put the keyword let before its name. Let's declare, for example, the variable named a:

let a;

After the variable declaration, you can write to it (they say to assign to it) some value, such as some number or string.

Writing data to a variable is done using the assignment operation =. Let's, for example, write the number 3 into the variable a:

let a = 3;

And now let's display the contents of this variable on the screen using the alert function:

let a = 3; // declaring a variable and assigning a value to it alert(a); // shows 3

It is not necessary to write the value into the variable immediately after the declaration. You can first declare a variable and then assign a value to it:

let a; // declaring a variable a = 3; // assigning value to it alert(a); // displays the value of the variable on the screen

As you see, let is written only once before a variable name - when you declare this variable. To use a variable further, you need only write the name of this variable.

Create the variable num and assign the value 123 to it. Display the value of this variable to the screen using the alert function.