Monday, September 7, 2009

"Enter" submits my ASP.NET form!

ASP.NET encourages web pages to be written as one big <form>, and every interaction with it to be a POST to the server ("Postback" in ASP.NET). This means pages often have multiple auto-generated <input type="submit"> elements.

On some browsers, pressing Enter causes the first submit button to be "clicked". In pages with many such buttons, that's usually not what you want. As a hack to make "Enter" do nothing on an already-built page, I added the following before any other submit button:

<div style="visibility:hidden;height:0;">
  <input type="submit" value="Dummy" onclick="return false;" />

Now this do-nothing, invisible submit button "catches" the Enter and prevents the next button from being "clicked". This requires JavaScript turned on, but ASP.NET's "Postbacks" require them anyway, so no big loss.

Implementation note: using 'display:none;' caused the browser to ignore it, so I had to resort to 'visibility:hidden;' and then 'height:0;' to impact the layout as little as I could. There could be cross-browser styling issues here, my specific case didn't need anything special.