How to check data type in javascript

Question: How to check data type in javascript

Answer:

All data type variables.

var booleanData = true; 
var intData = 95;
var floatData = 1.55;
var stringData = "String Data";
var symbolData = Symbol('Symbol Data Type');
var undefinedData;
var objectData = {}; //object
var newStringData = new String( "String Data using new keyword" ); //Object

checking data type with 'typeof' javascript operator.

console.log(typeof booleanData);
console.log(typeof intData);
console.log(typeof floatData);
console.log(typeof stringData);
console.log(typeof symbolData);
console.log(typeof undefinedData);
console.log(typeof objectData);
console.log(typeof newStringData);

Output:

boolean
number
number
string
symbol
undefined
object
object

null: JavaScript gave us "object" as the type for null, which is not correct.

var nullData = null;
console.log(typeof nullData);

output:

object

We will use equality operator (==) or strict equality operator (===) to check null variable.

console.log(nullData == null);
console.log(nullData === null);

output:

true
true

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