JSFiddle - React, Tailwind, and code Playground

JavaScript

var obj = (function(func) {
    var variable;

    return {
        get something() {
            return variable;
        },

        set something(value) {
            variable = value;
            func();
        }
    };
})(function() {
    alert(123);
});
        
obj.something = 'foo';
alert(obj.something);