Helper function that fires when an object becomes avaiable

whenDefined.js

//Inspired by http://fokkezb.nl/2016/04/14/how-to-wait-for-a-javascript-variable-to-be-defined/

//var console = document.getElementById('console');
//console.innerText = 'not loaded';

var whenDefined = function($context, $variable, $callback){

    if( $context[$variable] ){
        $callback();
    } else {
      
        Object.defineProperty($context, $variable, {
            configurable: true,
            enumerable: true,
            writeable: true,
            get: function() {
                return this['_' + $variable];
            },
            set: function(val) {
                this['_' + $variable] = val;
                $callback();
            }
        });
    }
}


//whenDefined(window, 'intercomSettings', function() {
//  console.innerText = 'loaded';
//});


//setTimeout(function(){
//  window.intercomSettings = {blar: 'blar'};
//}, 3000)

whenDefined(window, 'intercomSettings', function() {
  console.log("defined1");
});
whenDefined(window, 'intercomSettings', function() {
  console.log("defined2");
});
setTimeout(function(){
  window.intercomSettings = {blar: 'blar'};
}, 3000);

defined1 is never printed because 2nd whenDefined override property (due to same context/variable) previously defined.