JavaScript is a dynamic programming language. It means you don't have to declare the type of a variable at the time of declaration, it's type will be determine automatically at the time of program execution i.e at run-time. This is the reason you can have the same variable for different types.
Javascript Dynamic typing Example
<script> var x = 42; // here, x is a Number var x = "DOT NET TRICKS"; // here, x is a String var x = true; // here, x is a Boolean var x = {name:'John', age:34}; // here, x is an Object </script>
JavaScript Data types
Typically, JavaScript has two types of data types : Primitive and Non-Primitive(Objects).

The typeof Operator
JavaScript typeof operator is used to find the type of a JavaScript variable.
<script> typeof "John" // returns string typeof 3.14 // returns number typeof Infinity; // returns number typeof NaN; // returns number typeof false // returns Boolean typeof null // returns object and this is bug in ECMA script5 typeof [1,2,3,4] // returns object typeof {name:'John', age:34} // returns object typeof function(){} // returns function typeof /^[0-9]$/I // returns object var d = new Date(); typeof d // returns object </script>
What do you think?
I hope, now you have the better understanding of JavaScript data type. I would like to have feedback from my blog readers. Your valuable feedback, question, or comments about this article are always welcome.
Share Article
Take our free skill tests to evaluate your skill!

In less than 5 minutes, with our skill test, you can identify your knowledge gaps and strengths.