MDN’s new design is in Beta! A sneak peek:

Firefox 19 para Desarrolladores

Esta página no está completa.

Firefox 19, based on Gecko 19, will ship in February 2013. This article provides information about the changes in this release that will affect developers. Nightly builds of what will become Firefox 19 are currently available on the Aurora channel.

Note: Items listed here are tentatively slated for Firefox 19; however, they may be held for a future release if testing shows they're not ready by the time Firefox 19 is due to ship. Please keep an eye on this page to stay up to date on the plans for Firefox 19.

Quieres ayudar a documentar Firefox 19? Visita la lista de bugs que necesitan ser revisados e inicia!

Cambios para desarrolladores


  • Los objetos Map y Set pasaron de tener un método size() a tener una propiedad size (bug 807001)
  • Los objetos Map and Set ahora tienen un método clear(). (bug 805003)


  • Support for the viewport-relative <length> units, vh, vw, vmin, and vmax, has landed (bug 503720)
  • CSS Flexbox has been unprefixed, but remains disabled by default (bug 801098).
  • The -moz-initial value has been unprefixed (bug 806068). -moz-initial will be kept for a while as an alias; however, authors are strongly encouraged to switch over to initial.
  • The CSS text-transform property now supports the full-width keyword, which allows a more seamless inclusion of Latin characters in text using ideographic fixed-width characters, like Chinese or Japanese (bug 774560).
  • The CSS page-break-inside has been implemented (bug 685012).
  • The CSS calc() function can now be used on <color-stop> (on <gradient>).
  • The CSS @page at-rule is now supported (bug 115199). Note that the pseudo-classes :first, :right, and :left are not yet implemented.
  • The :-moz-placeholder pseudo-class is replaced by the ::-moz-placeholder pseudo-element (bug 737786).



Support for XForms has been removed in Firefox 19.

Changes for add-on and Mozilla developers

Note: A key change in Firefox 19 is that nsresult is now strongly typed. This will help make it easier to detect bugs that are caused by mishandling of return values, but may cause existing code to break if it's making incorrect assumptions in this regard.

  • getBrowserSelection() now returns the selected text in a text input field. As a result, gContextMenu.isTextSelected will be true when the user selects text in a text input field that is not a password field. (bug 565717)
  • Dict.jsm: Dict() now takes a JSON String. Dict.toJSON() was added, and it returns a JSON String. (bug 727967)

See also

Older versions

Etiquetas y colaboradores del documento

 Colaboradores en esta página: Sebastianz, mannyatico
 Última actualización por: Sebastianz,