I love the way that as I am typing this question, I am seeing what I am typing appear below, and it makes errors much easier to spot. Can anyone enlighten me to the science or technique behind this - i'm thinking of using it as a better way to confirm email entry on a web form...

  • You'll get a better answer if you ask this question separately on StackOverflow.com (try to ask a more general question).
    – Rahul
    May 23, 2011 at 12:04
  • You'll need to emphasise that you want to implement it yourself otherwise the question is likely to get migrated to Meta Stack Overflow as people will think it's a question about the site.
    – ChrisF
    May 23, 2011 at 12:06

3 Answers 3


It works because it forces you to review your post. Now, other than seeing how the markup looks rendered, you could just look at your text in the input field, right?

But having it in a separate area makes a users mind make an extra note as its viewed as a separate entity. Since the mind see's its own words in another context (more of that of a post) we can review it with an almost new mind.

For example, I am sure you have experienced this. You stay up late writing a paper, finish and save then go to sleep. Then before you hand it in you review your fine work. All of a sudden you catch major mistakes you somehow missed when you were writing it. The same thing might happen when you return to a design or some other work.

Our mind needs the separation to view it as new, when its viewed as new we can better review it.

  • I find myself sometimes trying to edit the preview though. As I am reading the preview, I see something to change and naturally click there to position the cursor. Then I realise my mistake and finding the same point in the "real" edit field takes "work" because, of course, the relative position is different. Is that just me? The benefits out weigh that inconvenience though.
    – phinetune
    May 27, 2011 at 6:04

One big benefit of the preview view is that it lets you instantly see how your markup changes things. Humans tend to associate temporal locality with causation and by having a constantly updating preview area, you shrink the gap between action and result to almost nothing.

  • I find the preview panel useful for just this purpose. If I'm entering plain text then I am not concerned with the preview, but when I'm adding Quotes, Links etc it's very useful to see how those are displayed so I can make changes 'on the fly' without having to publish and then edit.
    – JonW
    May 31, 2011 at 9:42

Using Javascript, you can write a small script that listens to the "onkeyup" event that happens everytime you type a letter, and copy whatever you typed into a preview area in your HTML. That's basically what's happening here, although it's slightly more complicated because it also transforms the markdown and HTML you write in the textarea into actual HTML.

  • Thanks for the info on HOW to do it - anyone got any insight into WHY it works? I'd just like to understand the logic of why it was used on this site and any other applications that people may have applied it to. May 23, 2011 at 15:59
  • @Theshooglypeg It wasn't clear from your question that you were looking for the "why" as opposed to the "how". Can you rephrase it so we know better how to help you?
    – Rahul
    May 23, 2011 at 16:09

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