How to watch for variable changes at all levels in NodeJS

Question

I have this variable in NodeJS:

var toWatch = {
    count: 3,
    name: {
        first: "Foo",
        last: "Bar"
    }
}

And I want to fire a function when any value of it changes. For example, toWatch.name.first = "ABC" and toWatch.newProperty = 123 would both trigger this function.

How can I implement this function?

`->` https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy would be the only way. — Felix Kling, Sep 20 '17 at 21:04
It would generally always be better to hook into whatever is changing the value to begin with. — adeneo, Sep 20 '17 at 21:05
Possible duplicate of [Object.watch() for all browsers?](https://stackoverflow.com/questions/1029241/object-watch-for-all-browsers) — Get Off My Lawn, Sep 20 '17 at 21:08
@Pointy, good lib, although looking at the source, it seems to be polling the variables. I am looking for a solution that will work with extremely large objects. — adelriosantiago, Sep 20 '17 at 21:13
The linked code works in node. https://gist.github.com/eligrey/384583#gistcomment-1429714 — Get Off My Lawn, Sep 20 '17 at 21:13

score 0 · Answer 1 · answered Sep 20 '17 at 21:04

0

You can use Proxy to observe set and get at a JavaScript object.

answered Sep 20 '17 at 21:04

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Can you elaborate? Is that a variable property? – adelriosantiago Sep 20 '17 at 21:07
@adelriosantiago See first [link](https://stackoverflow.com/questions/46331711/how-to-watch-for-variable-changes-at-all-levels-in-nodejs/46331750#comment79624240_46331711) posted at Question, also [Is JavaScript Proxy supposed to intercept direct changes to underlying object like Object.Observe?](https://stackoverflow.com/q/40011480/), [How to detect when a JavaScript object variable is accessed?](https://stackoverflow.com/q/41405080/) – guest271314 Sep 20 '17 at 21:10

How to watch for variable changes at all levels in NodeJS

1 Answers1