Does .css() automatically add vendor prefixes?

Question

I have some code:

$("#" + this.id).css("border-radius",this.radius + "px");
$("#" + this.id).css("-moz-border-radius",this.radius + "px");
$("#" + this.id).css("-webkit-border-radius",this.radius + "px");

I am trying to improve lines like this by using JSON to apply them (as shown in jQuery's docs) or by removing the vendor prefix versions completely.

Does jQuery's .css() method automatically apply any required vendor prefixes when changing CSS properties on an element?

Answer 1

This is now confirmed in the official docs: http://api.jquery.com/css/

Setter ( .css( propertyName, value ) )

As of jQuery 1.8, the .css() setter will automatically take care of prefixing the property name. For example, take .css( "user-select", "none" ) in Chrome/Safari will set it as -webkit-user-select, Firefox will use -moz-user-select, and IE10 will use -ms-user-select.

Getter ( .css( propertyName ) )

The .css() method is a convenient way to get a computed style property from the first matched element, especially in light of the different ways browsers access most of those properties (the getComputedStyle() method in standards-based browsers versus the currentStyle and runtimeStyle properties in Internet Explorer prior to version 9) and the different terms browsers use for certain properties. For example, Internet Explorer's DOM implementation refers to the float property as styleFloat, while W3C standards-compliant browsers refer to it as cssFloat. For consistency, you can simply use "float", and jQuery will translate it to the correct value for each browser.

It doesn't explicitly mention vendor prefixes in the getter context but it's easy to test. For example, $element.css('border-radius') on Chrome returns values set as border-radius or -webkit-border-radius and ignores values set as -moz-border-radius.

Just keep in mind that it's inconsistent across browsers for shorthand properties:

Retrieval of shorthand CSS properties (e.g., margin, background, border), although functional with some browsers, is not guaranteed. For example, if you want to retrieve the rendered border-width, use: $( elem ).css( "borderTopWidth" ), $( elem ).css( "borderBottomWidth" ), and so on.

Answer 2

As @zeroflagL wrote it appears that since jQuery 1.8.0 .css() does add browser specific prefixes (see this).

In earlier versions this is not done automatically by jQuery's .css(). You will have to do it by yourself or you can use jQuery's .cssHooks() to add vendor prefixes.

Code example from here:

(function($) {
  if ( !$.cssHooks ) {
    throw("jQuery 1.4.3+ is needed for this plugin to work");
    return;
  }

  function styleSupport( prop ) {
    var vendorProp, supportedProp,
        capProp = prop.charAt(0).toUpperCase() + prop.slice(1),
        prefixes = [ "Moz", "Webkit", "O", "ms" ],
        div = document.createElement( "div" );

    if ( prop in div.style ) {
      supportedProp = prop;
    } else {
      for ( var i = 0; i < prefixes.length; i++ ) {
        vendorProp = prefixes[i] + capProp;
        if ( vendorProp in div.style ) {
          supportedProp = vendorProp;
          break;
        }
      }
    }

    div = null;
    $.support[ prop ] = supportedProp
    return supportedProp;
  }

  // check for style support of your property 
  // TODO by user: swap out myCssPropName for css property
  var myCssPropName = styleSupport("myCssPropName");

  // set cssHooks only for browsers that
  // support a vendor-prefixed border radius
  if (myCssPropName && myCssPropName !== 'myCssPropName') {
    $.cssHooks["myCssPropName"] = {
      get: function(elem, computed, extra) {
        // handle getting the CSS property
        return $.css(elem, myCssPropName);
      },
      set: function(elem, value) {
        // handle setting the CSS value
        elem.style[myCssPropName] = value;
      }
    };
  }
})(jQuery);

Answer 3

jQuery DOES add vendor prefixes. It first checks for the presence of the standard property and if it's not found for a vendor prefixed version. From the source:

// return a css property mapped to a potentially vendor prefixed property
function vendorPropName( style, name ) {
    // shortcut for names that are not vendor prefixed
    if ( name in style ) {
      return name;
     }

    // check for vendor prefixed names
    ...

I don't know since which version, but I think 1.8.