Javascript Scriptaculous Autocomplete可在加载页面时激活

是否有一种方法可以在加载页面时启动Scriptaculous的自动完成功能，使用inputfield中的默认单词进行搜索

像这样的

<input type="text" id="autocomplete" class="autocomplete_input" name="autocomplete_parameter" value="friends"/>
<span id="indicator1" style="display: none">
loading
</span>
<div id="autocomplete_choices" class="autocomplete">

</div>
<script type="text/javascript">
function AutoComp() {
var myAutoCompleter = new Ajax.Autocompleter("autocomplete", "autocomplete_choices",         "url", {indicator: 'indicator1',});
}
document.onLoad = AutoComp.activate();
</script>

我的错

var myAutoCompleter = new Ajax.Autocompleter("autocomplete", "autocomplete_choices", "api/usersearch/", {indicator: 'indicator1'});

document.observe("dom:loaded", function() {
myAutoCompleter.activate();
});
</script>

这就成功了