Eventful Javascript
let data = {child:[]}; treevent.Listen(data, "child[*].name[0]", (path, params, type, index, oldValue, newValue) => { console.log("woah..."); } ); data.child.unshift({name: ["first", "last"]}) For any front-end developers out there, you may have noticed the increasing popularity of reactive / event-driven / data-binding architectures. Call it what you like, but things like React , RxJS , Angular , Web Components , Meteor , Firebase , ... etc are all built along similar principles. Whenever asked about them, I always recommend usage (it's a much nicer style of coding that a non-binding way) but I also tend to complain that ' arrays aren't done properly ', which understandably confuses people, as it's intentionally reductionist. There's obvious things, like Firebase's lack of native array support , but I realized that what I more meant was that array mutations weren't handled well, which means