Animate element to auto height with jQuery

Solution 1:

1. Save the current height:

   var curHeight = $('#first').height();
   

2. Temporarily switch the height to auto:

   $('#first').css('height', 'auto');
   

3. Get the auto height:

   var autoHeight = $('#first').height();
   

4. Switch back to curHeight and animate to autoHeight:

   $('#first').height(curHeight).animate({height: autoHeight}, 1000);
   

And together:

var el = $('#first'),
    curHeight = el.height(),
    autoHeight = el.css('height', 'auto').height();
el.height(curHeight).animate({height: autoHeight}, 1000);

Solution 2:

IMO this is the cleanest and easiest solution:

$("#first").animate({height: $("#first").get(0).scrollHeight}, 1000 );

Explanation: The DOM already knows from its initial rendering what size the expanded div will have when set to auto height. This property is stored in the DOM node as scrollHeight. We just have to fetch the DOM Element from the jQuery Element by calling get(0) and then we can access the property.

Adding a callback function to set the height to auto allows for greater responsiveness once the animation is complete (credit chris-williams):

$('#first').animate({
    height: $('#first').get(0).scrollHeight
}, 1000, function(){
    $(this).height('auto');
});

Solution 3:

This is basically the same approach as the answer by Box9 but I wrapped it in a nice jquery plugin that takes the same arguments as a regular animate, for when you need to have more animated parameters and get tired of repeating the same code over and over:

;(function($)
{
  $.fn.animateToAutoHeight = function(){
  var curHeight = this.css('height'),
      height = this.css('height','auto').height(),
      duration = 200,
      easing = 'swing',
      callback = $.noop,
      parameters = { height: height };
  this.css('height', curHeight);
  for (var i in arguments) {
    switch (typeof arguments[i]) {
      case 'object':
        parameters = arguments[i];
        parameters.height = height;
        break;
      case 'string':
        if (arguments[i] == 'slow' || arguments[i] == 'fast') duration = arguments[i];
        else easing = arguments[i];
        break;
      case 'number': duration = arguments[i]; break;
      case 'function': callback = arguments[i]; break;
    }
  }
  this.animate(parameters, duration, easing, function() {
    $(this).css('height', 'auto');
    callback.call(this, arguments);
  });
  return this;
  }
})(jQuery);

edit: chainable and cleaner now