How Can I Detect Variable Changes in JavaScript?

Listening for Variable Changes in JavaScript

In JavaScript, it is often desirable to be notified when the value of a variable changes. This can be achieved using the Proxy object, introduced in 2018. The Proxy object allows for the creation of a proxy that intercepts property changes and responds accordingly.

To use the Proxy object, first create a target object to be observed:

Next, create a proxy using the Proxy object, specifying a callback to be executed when a property is set:

When a property of the target object is set via the proxy, the callback function is executed. For example:

The Proxy object has drawbacks in that it is not available in older browsers and may not behave as expected with certain objects. For observing changes in nested objects, specialized libraries such as Observable Slim can be used.

Observable Slim

Observable Slim is a library designed for observing changes in nested objects. To use it, first create the object to be observed:

Then, use Observable Slim to create a proxy with the create function, specifying a callback to be executed when changes occur:

When a property of the observed object changes, the callback function is executed. For example:

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