how to check the data type in javascript code example

Example 1: get type of var js

function doSomething(x) {
  if(typeof(x) === 'string') {
    alert('x is a string')
  } else if(typeof(x) === 'number') {
    alert('x is a number')
  }
}

Example 2: check data type in javascript

typeof("string"); //string
typeof(123); //number

Example 3: get type of var js

var x = 12345; 
console.log(typeof x) // number
x = 'string'; 
console.log(typeof x) // string
x = { key: 'value' };
console.log(typeof x) // object

Example 4: check data type in js

var x = "Hello World";
typeof x; // "string"