Example

object.js

 var learn = {
	programmelanguage:{
        web: {fontend : "HTML-CSS-JS",
			  backend: ".NET-MONGODB-DATABASE"},
		web_app: "NODEJS-REACT-ANGULAR-JS++",
		mobile: {
				android: "JAVA-KOTLIN",
				ios: "OBJECTIVE_C..."},
		desktop: {
				windows: "C-C++-.NET...",
				linux: "PYTHON..."}
		}};
console.log(learn.programmelanguage.web.fontend);
console.log(learn.programmelanguage.mobile.android);
learn.programmelanguage.web_app="delete cmnr!";
console.log(learn.programmelanguage.web_app);
for (let a in learn) {
console.log(a, learn[a]);}