How to Show hide toggle display a DIV using javascript

In many cases developers need to show hide or toggle div container based on user requirement. Some of SEO specialists told that hiding a div is against SEO. But I want to tell that if your div appear with unchanged contents by user interaction then it’s ok for SEO. In many cases like you want to display a popup type window (which is basically a div) then you need to show or hide a div. Here in