how to change json value in javascript code example

Example 1: change js to json

var obj = {name: "Martin", age: 30, country: "United States"};
 
// Converting JS object to JSON string
var json = JSON.stringify(obj);
 
console.log(json);
// Prints: {"name":"Martin","age":30,"country":"United States"} 
"https://www.tutorialrepublic.com/faq/how-to-convert-js-object-to-json-string.php"

Example 2: create a json object in javascript

var employee = {
  "firstName": firstName,
  "lastName": lastName
}