<script type="text/javascript">
window.onload = function(){
??? // JS實現選項卡切換
??? //獲取標題
??? var li = document.getElementsByTagName("li");
??? //獲取內容
??? var div = document.getElementsByName("div");
??? var len = div.length;
??? //選項卡內容多個，需要循環遍歷來操作，得知哪個選項卡和哪個選項內容匹配
??? for(var i=0;i<len;i++){
??????? li[i].index = i;
??????? li[i].onclick = function(){
??????????? for(var j=0;j<len;j++){
??????????????? li[j].className = "";
??????????????? div[j].style.display = "none";
??????????? }
??????????? this.className = "fang";
??????????? div[this.index].style.display = "block";
??????? }
??? }
}
</script>

其中li[i].index = i;和div[this.index].style.display = "block";這句是什么用？為什么一定要定義一個index呢？直接用i怎么實現不了？