how to check if a string is in a string in javascript code example

Example 1: check if word is in string javascript

var str = "Hello world, welcome to the universe.";
var n = str.includes("world");

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.