Why doesn't jQuery.animate() work for CSS3 rotations, and how can we achieve cross-browser animated rotations using jQuery?

Cross-Browser Rotation with jQuery.animate()

Problem

Cross-browser rotation with jQuery.animate() proves challenging due to the non-animation capabilities of CSS-Transforms. The code below demonstrates the issue:

$(document).ready(function () { 
    DoRotate(30);
    AnimateRotate(30);
});

function DoRotate(d) {

    $("#MyDiv1").css({
          '-moz-transform':'rotate('+d+'deg)',
          '-webkit-transform':'rotate('+d+'deg)',
          '-o-transform':'rotate('+d+'deg)',
          '-ms-transform':'rotate('+d+'deg)',
          'transform': 'rotate('+d+'deg)'
     });  
}

function AnimateRotate(d) {

        $("#MyDiv2").animate({
          '-moz-transform':'rotate('+d+'deg)',
          '-webkit-transform':'rotate('+d+'deg)',
          '-o-transform':'rotate('+d+'deg)',
          '-ms-transform':'rotate('+d+'deg)',
          'transform':'rotate('+d+'deg)'
     }, 1000); 
}

Rotation works when using .css(), but not with .animate(). Why? And how can we overcome this obstacle?

Solution

While CSS-Transforms lack direct animation support in jQuery, a workaround is possible using a step-callback like this:

function AnimateRotate(angle) {
    // Cache the object for performance
    var $elem = $('#MyDiv2');

    // Use a pseudo object for the animation (starts from `0` to `angle`)
    $({deg: 0}).animate({deg: angle}, {
        duration: 2000,
        step: function(now) {
            // Use the `now` parameter (current animation position) in the step-callback
            $elem.css({
                transform: 'rotate(' + now + 'deg)'
            });
        }
    });
}

This method allows for the rotation of elements using jQuery. Additionally, jQuery 1.7 eliminates the need for CSS3 transform prefixes.

jQuery Plugin

To simplify the process, create a jQuery plugin like this:

$.fn.animateRotate = function(angle, duration, easing, complete) {
  return this.each(function() {
    var $elem = $(this);

    $({deg: 0}).animate({deg: angle}, {
      duration: duration,
      easing: easing,
      step: function(now) {
        $elem.css({
           transform: 'rotate(' + now + 'deg)'
         });
      },
      complete: complete || $.noop
    });
  });
};

$('#MyDiv2').animateRotate(90);

Optimized Plugin

For better efficiency and flexibility, an optimized plugin can be created:

$.fn.animateRotate = function(angle, duration, easing, complete) {
  var args = $.speed(duration, easing, complete);
  var step = args.step;
  return this.each(function(i, e) {
    args.complete = $.proxy(args.complete, e);
    args.step = function(now) {
      $.style(e, 'transform', 'rotate(' + now + 'deg)');
      if (step) return step.apply(e, arguments);
    };

    $({deg: 0}).animate({deg: angle}, args);
  });
};

Usage

The plugin provides two ways to use it:

1. Single line syntax:

$(node).animateRotate(90);
$(node).animateRotate(90, function () {});
$(node).animateRotate(90, 1337, 'linear', function () {});

2. Object syntax (preferred for more than three arguments):

$(node).animateRotate(90, {
  duration: 1337,
  easing: 'linear',
  complete: function () {},
  step: function () {}
});

Conclusion

This plugin enables cross-browser CSS rotation using jQuery's animation capabilities. It eliminates the need for manual rotation calculations and provides a convenient and optimized way to achieve rotation effects.

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