Define Data Type When Declaring Variable in JavaScript

In JavaScript, variables are defined using the var keyword followed by the variable name. Before you use a variable in a JavaScript program, you must declare it. Variables are declared with the var keyword as follows.

var rank;

A data type isn’t needed in JavaScript. Variables in JavaScript are not handled like other strong typed language C++, Java, etc.
Storing a value in a variable is called variable initialization. You can do variable initialization at the time of variable creation or at a later point in time when you need that variable.

<script>
   var name = "Amit";
   var rank = 2;
</script>