how to get somethings type javascript code example

Example 1: is string javascript

function isString(value) {
	return typeof value === 'string' || value instanceof String;
}

isString(''); // true
isString(1); // false
isString({}); // false
isString([]); // false
isString(new String('teste')) // true

Example 2: check data type in javascript

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