JS Error subscriptionChange()

Hello,

I am using your plugin and i try to catch the subscriptionChange event but i got an error.

How can i perform this ?

my code :

window.OneSignal.push(function() {
window.OneSignal.init(window._oneSignalInitOptions);
let searchParams = new URLSearchParams(window.location.search)
                                if (searchParams.has("login"))
                                {
                                    if (searchParams.get("login") == "true")
                                    {
                                        saveOneSignalDataToUser();
                                    }
                                }
                                else
                                {
                                    saveOneSignalDataToUser();
                                }
                                OneSignal.on("subscriptionChange", function(isSubscribed) {
                                    //console.log("The user's subscription state is now:", isSubscribed);
                                    if (isSubscribed)
                                    {
                                        saveOneSignalDataToUser();
                                    }
                                });
                            });

This line throw me an error : OneSignal.on(“subscriptionChange”, function(isSubscribed)

TypeError: OneSignal.on is not a function. (In ‘OneSignal.on(“subscriptionChange”, function (isSubscribed) {

Thanks for your help !