# JavaScript Variables

Paul Tomoiu

●

Javascript,

frontend,

web

●

Published 2022-12-03

This tutorial explains to you how you can work with JavaScript variables.

Here is a code you can test:

<!doctype html>
<html lang="en">
<head>
    <meta http-equiv="Content-Language" content="en-us">
    <meta charset="utf-8"> 
</head>
 
<body>
    <script type="text/javascript">
        var number1 = 1000;
        var number2 = 0.12; 
        var x1 = "JavaScript";
        var x2 = "AJAX";
        var varboolean = true;
 
        alert(number1 + number2);
         
        alert("I learn "+x1+" and "+x2);
        alert(varboolean);
         
        var a1 = 1;
        var a2 = 2;
        var a = a1 + a2;
        alert(a);
         
        var b = 20 + 30 + "40" + 10 + 20;
        alert(b);
         
        var c = "90"+20;
        alert(c);
 
    </script>
</body>
</html>

You will see the following results (the results will show you how JavaScript variables are used in JavaScript code):

Here are the things to know:

in JavaScript you don't need to define (you cannot define) a variable type. The type is "created" automatically
with "+" sign you can add 2 numbers and concatenate 2 variables
a boolean variable can have 2 values: true or false (nothing special here)

Info

When we have :

var b = 20 + 30 + "40" + 10 + 20;
alert(b);

20 + 30 : the result is a number (50)
50 + "40" : the result is a string ("5040"). After that, all the number in a concatenation are seen like strings.