how to know if the value is string in javascript code example

Example 1: if variable is string javascript

var booleanValue = true; 
var numericalValue = 354;
var stringValue = "This is a String";
var stringObject = new String( "This is a String Object" );
alert(typeof booleanValue) // displays "boolean"
alert(typeof numericalValue) // displays "number"
alert(typeof stringValue) // displays "string"
alert(typeof stringObject) // displays "object"

Example 2: check if value is a string javascript

let eventValue = event.target.value;

    if (/^\d+$/.test(eventValue)) {
      eventValue = parseInt(eventValue, 10);
    }

//If value is a string, it converts to integer. 

//Otherwise it remains integer.