Move node on media query

class Appender{
    constructor(bigScreenParent, smallScreenParent, child, media){
        this._bigScreenParent = bigScreenParent
        this._smallScreenParent = smallScreenParent
        this._child = child
        this._media = media
    }
    get bigScreenParent(){
        return this._bigScreenParent
    }
    get smallScreenParent(){
        return this._smallScreenParent
    }
    get child(){
        return this._child
    }
    get media(){
        return this._media
    }
    addChild(){
      // if screen matches the media query, then move element to first child position of selected parent
        if (this._media.matches){
            this._smallScreenParent.insertAdjacentElement('afterbegin', this._child)
        }else this.bigScreenParent.insertAdjacentElement('afterbegin', this._child)
    }
}

//if screen is big enough, display #sidebarBlurb on sidebar - otherwise, show it on top of main 
let bigScreenParent = document.getElementById('sidebar')
let smallScreenParent = document.getElementById('main')
let child = document.getElementById('sidebarBlurb')

//media query
let media = window.matchMedia("(max-width: 1280px)")

let prependThis = new Appender(bigScreenParent, smallScreenParent, child, media)

//run it on load to keep looks consistent
window.onload = prependThis.addChild()
//add an event listener in case screen size changes
window.matchMedia('(max-width: 1280px)').addEventListener('change', () => prependThis.addChild())