Answer by Mohamed Mufeed for How to get value from a function in JavaScript

I am not quite sure what you want. But I believe this is what you are trying.

document.addEventListener("init", function (event) {    let page = event.target;     var setImage = function (url) {        var imgDiv = document.getElementById("image-div");        var img = document.createElement('img');        img.src = url;        imgDiv.appendChild(img);    }    $("#container").simpleCalendar({        onCalendarLoad : function (date, events) {            if (page.id === 'page1') {                setImage(events[0].img);            } else if (page.id === 'page2') {                // do something else            }        }    }}