Function isGone

mini-react/src/mini-react.js:115–115

(prev, next)

    const isProperty = key => key !== "children" && !isEvent(key)
    const isNew = (prev, next) => key => prev[key] !== next[key]
    const isGone = (prev, next) => key => !(key in next)
    
    function updateDom(dom, prevProps, nextProps) {
      //Remove old or changed event listeners