Question

I’m using tables in my document, and I want to be able to have a user submit a new item to a list, then have it “automagically” appear at the top of the list (yes, this would be easier with DIVs but working with what I have).

I’m using jQuery, and clone() to create a copy of the most recent table row, then using fadeIn() to display the new item after I update and add it to the top of the list. Because internally jQuery converts elements (assuming DIVs) to ‘block’, I’m also changing the css class to ‘table-row’. It works fine.

The whole code is here:

    var row = $("tbody tr:first").clone().hide(); // clone and then set display:none
    row.children("td[class=td-date]").html("today");
 // set some properties
    row.children("td[class=td-data]").html("data");
    row.children("td[class=td-type]").html("type");
// fadeIn new row at the top of the table.
    row.insertBefore("tbody tr:first").stop().fadeIn(2000).css("display","table-row"); 

The problem is that if I run the process too quickly – i.e. before the fadeIn completes, the “clone()” command ends up cloning the opacity as well.

I can actually get it to work in Firefox using by adjusting the first line above:

 var row = $("tbody tr:first").clone().css("opacity","1").hide();

My concern now is that I’m not sure that any of this is being done efficiently, and/or that “opacity” is cross-browser safe to rely upon.

Has anyone done something like this before, and can offer any pointers on a more reliable approach?

Answer 1

opacity as a jQuery css attribute is safe cross-browser as it irons out the browser differences in the implementation. Here’s the source

// IE uses filters for opacity
if ( !jQuery.support.opacity && name == "opacity" ) {
  if ( set ) {
    // IE has trouble with opacity if it does not have layout
    // Force it by setting the zoom level
    elem.zoom = 1;

    // Set the alpha filter to set the opacity
    elem.filter = (elem.filter || "").replace( /alpha\([^)]*\)/, "" ) +
    (parseInt( value ) + '' == "NaN" ? "" : "alpha(opacity=" + value * 100 + ")");
  }

  return elem.filter && elem.filter.indexOf("opacity=") >= 0 ?
  (parseFloat( elem.filter.match(/opacity=([^)]*)/)[1] ) / 100) + '': "";
}

The following works.
Working Demo – add /edit to the URL to play with it.

  // stop previous animation on the previous inserted element
  var prevRow = $("tbody tr:first").stop(true,true);

  var row = prevRow.clone();
  row.children("td.td-date").text("today");
  row.children("td.td-data").text("data");
  row.children("td.td-type").text("type");

  row.fadeIn(2000).prependTo("tbody");