typeof variable;

> typeof "foo"

"string"

> typeof true

"boolean"

> typeof 42

"number"

​

// You can use the built-in method 'typeof' in order to check the variable datatype

​

//examples:

​

typeof "hello" // "string"

​

//or

var a = 1;

typeof(a);

//the output will be > 'number'

let store = [1,2,3]; console.log(typeof store);

typeof operando

if(typeof variable == 'object'){

  //

}

> typeof "foo"

"string"

> typeof true

"boolean"

> typeof 42

"number"

There are two scopes of variables:

​

- Global variables - Defined anywhere in code

- Local variables - Defined in only function

var var1 = "Hello, World!";

console.log(var1); // Output: Hello, World!

​

var1 = 42; // You can change the value of a variable declared with 'var'

console.log(var1); // Output: 42