$ not defined but jQuery IS defined in Wordpress

Question

What might cause Firefox to tell me $ is not defined, but using 'jQuery' works as expected.

I'm on Wordpress 3.4 and Wordpress comes packaged with jQuery. Is it something specific to Wordpress?

Answer 1

jQuery.noConflict() has been called. To resolve this with a minimum amount of code change do this.

Before:

$("your").code(function () {
  $("that").uses($.all("over").the("place"));
});

After:

(function ($) {
  $("your").code(function () {
    $("that").uses($.all("over").the("place"));
  });
})(jQuery);

Answer 2

jQuery在WordPress中以noConflict模式在文档状态下工作： http ://codex.wordpress.org/Function_Reference/wp_enqueue_script#jQuery_noConflict_wrappers