Function isProperty

mini-react/src/mini-react.js:113–113

    
    const isEvent = key => key.startsWith("on")
    const isProperty = key => key !== "children" && !isEvent(key)
    const isNew = (prev, next) => key => prev[key] !== next[key]
    const isGone = (prev, next) => key => !(key in next)