javascript check if there isn't a querystring parameter of code example

Example: javascript read query parameters

// example url: https://mydomain.com/?fname=johnny&lname=depp
const queryString = window.location.search;
console.log(queryString);
// ?fname=johnny&lname=depp

const urlParams = new URLSearchParams(queryString);

const firstName = urlParams.get('fname');
console.log(firstName);
// johnny

const lastName = urlParams.get('lname');
console.log(lastName);
// depp