表单上有class 的 就必须填写
这是我写的 不能运行<script>
function tianxie(){
var xings = document.getElementsByTagName("bitian");
for(var i=0;i<xings.length;i++){
if(xings[i]){
alert("必须填写");
}
}
}
</script>
</head>
<body>
<form>
<input type="text" class="bitian">
<input type="text" class="bitian">
<input type="text" name="heihei" >
<input type="submit" value="提交 " onclick="tianxie();">
</form>
</body>
</html>
这是我写的 不能运行<script>
function tianxie(){
var xings = document.getElementsByTagName("bitian");
for(var i=0;i<xings.length;i++){
if(xings[i]){
alert("必须填写");
}
}
}
</script>
</head>
<body>
<form>
<input type="text" class="bitian">
<input type="text" class="bitian">
<input type="text" name="heihei" >
<input type="submit" value="提交 " onclick="tianxie();">
</form>
</body>
</html>
<script>
function tianxie(){
var o= document.getElementsByTagName("INPUT");
for(var i=0;i<o.length;i++){
if(o[i].className=='bitian'&&o[i].value.length==0){
alert("必须填写");
o[i].focus();
return false;
}
}
}
</script>
</head>
<body>
<form>
<input type="text" class="bitian">
<input type="text" class="bitian">
<input type="text" name="heihei" >
<input type="submit" value="提交 " onclick="return tianxie();">
</form>
</body>
</html>
bitian不是标签(Tag),你用var xings = document.getElementsByTagName("bitian"); 自然抓不到了
标签指的是INPUT,BODY,BUTTON,FORM等等