为什么JavaScript切换代码不起作用？

Question

I have added the Prototype library to my site, then add the following code. but when i click the span, the ul content is not hidden. the link href still work.

Event.observe(window, 'load', function() {
    Event.observe('.block-category li.parent span', 'click', function(e){
        $('.block-category li.parent ul').toggle();
        e.preventDefault();

    });
});

html:

    <div class="block block-category">
    <li class="level-top  parent">
    <a href="example.com/...."><span>text one</span></a>
    <ul> //the 1 ul
    <li><a><span>....</span></a></li>
    <li><a><span>....</span></a></li>
    <li><a><span>....</span></a></li>
    <li><a><span>....</span></a></li>
    </ul>
    </li>

    <li class="level-top"><a href="..."><span>....</span></a></li>


  <li class="level-top  parent">
    <a href="example.com/...."><span>text two</span></a>
    <ul> //the 2 ul
    <li><a><span>....</span></a></li>

    </ul>
    </li>
  <li class="level-top  parent">
    <a href="example.com/...."><span>text three</span></a>
    <ul>
    <li><a><span>....</span></a></li>
    <li><a><span>....</span></a></li>
    </ul>
    </li>
    </div>

thank you.

ps : when click text one , the the 1 ul toggle. when click * text two *the 2 ul toggle, ...

Answer 1

You are using CSS selectors as arguments to Prototype's $() and Event.observe() functions. Neither of these functions accepts a selector. They both expect element IDs instead.

You can use $$() instead of $() and give it a selector. Note that this returns an array of extended elements and not just a single one.

http://api.prototypejs.org/dom/Event/observe/
http://api.prototypejs.org/dom/dollar/
http://api.prototypejs.org/dom/dollar-dollar/

Answer 2

You should try $$ to select multiple elements and then call observe for each one of them:

Event.observe(window, 'load', function() {
    $$('.block-category li.parent > a span').each(function (element) {
        element.observe('click', function (e) {
            e.element().up().next('ul').toggle();
            e.preventDefault();
        });
    });
});