表单切换，用回车键替换Tab健(不支持IE)

<div> 
<form> 
<input name="a" tab="1" /> 
<input name="a" tab="3" /> 
<input name="a" tab="2" /> 
<input name="a" tab="5" /> 
<input name="a" tab="4" /> 
<input type="submit" value="submit" /> 
</form> 
</div> 
<script type="text/javascript"> 
var inputs = document.getElementsByTagName("input"); 
for (i = 0; i < inputs.length; i++) { 
inputs[i].onkeydown = function(e){ 
if (e.keyCode == 13) { 
var input = getInputByTab(parseInt(this.getAttribute("tab")) + 1); 
if (input) { 
input.focus(); 
return false; 
} 
} 
} 
} 
function getInputByTab(t) { 
for (i =0; i < inputs.length; i++) { 
if (inputs[i].getAttribute("tab") == t) 
return inputs[i]; 
} 
return false; 
} 
</script>