Let's say you have a file named app.js that contains the following.

const json = '{"my_string": "Hello World", "my_boolean": true, "my_integer" :42}';
const obj = JSON.parse(json);

console.log(obj.my_string);
console.log(obj.my_boolean);
console.log(obj.my_integer);

If you use the node CLI to run app.js, the following should be displayed as stdout on your console.

~]$ node app.js
Hello World
true
42