getElementsByClassName

標題：自定義getElementsByClassName函式

<script type="text/javascript">
function getElementsByClassName(className, parentElement){
    if (typeof parentElement == 'string'){
        parentElement = document.getElementById(parentElement);
    } else if (typeof parentElement != 'object' || typeof parentElement.tagName != 'string'){
        parentElement = document.body;
    }
    var elems = parentElement.getElementsByTagName("*");
    var result=[];
    for (i=0; j=elems[i]; i++) {
        if ((" "+j.className+" ").indexOf(" "+className+" ")!=-1) {
            result.push(j);
        }
    }
    return result;
}
function test() {
    var divs1 = getElementsByClassName('myclass');
    var divs2 = getElementsByClassName('myclass','parent');
    var divs3 = getElementsByClassName('myclass',document.getElementById('parent'));
    alert(divs1[0].innerText);
    alert(divs2[1].innerText);
    alert(divs3[2].innerText);
}
</script>
<a href="javascript:test();">Click me</a>
<div id="parent">
    <div class="myclass">1</div>
    <div class="myclass">2</div>
    <div class="myclass">3</div>
</div>

說明：
自定義getElementsByClassName函式，
可掃描指定id內之所有class名稱並以陣列儲存。