.className問題 ,加粗部分
?</style>
?? <script>
??? window.onload = function(){
?????? var container = document.getElementById('container');
??? var listImg = document.getElementById('listImg');
??? var buttons = document.getElementById('buttons');
??? var next = document.getElementById('next');
??? var prev = document.getElementById('prev');
??? var index = 1;
??? function animate(offset){
???????? var newlist = parseInt(listImg.style.left)+offset;
????? listImg.style.left = newlist + 'px';
???? if(newlist > -700){
???????? listImg.style.left = -3500 + 'px';
???? }
???? if(newlist < -3500){
???????? listImg.style.left = -700 + 'px';
???? }
??? }
??? function showButtons(){
??????? buttons[index-1].className = 'on';???? 在這用className瀏覽器報(bào)??‘Uncaught TypeError: Cannot set property 'className' of undefined?’ 這個(gè)錯(cuò)呢
??? }
??? next.onclick = function(){
??????? showButtons();
??????? animate(-700);
??? }
??? prev.onclick = function(){
??????? animate(700);
??? }
??? }
???
?? </script>
2016-06-09
注意你第六行寫的是var buttons = document.getElementById('buttons');這樣獲取的只是一個(gè)對(duì)象,此時(shí)buttons[index-1]這個(gè)是不存在的,自然也沒有相對(duì)應(yīng)的className,應(yīng)當(dāng)改成var buttons=document.getElementById('buttons').getElementsByTagName('span'),此時(shí)buttons才是一個(gè)數(shù)組
2016-05-23
是不是js代碼放的位置有問題?