Javascript 使用 document.getElementsByName() 不起作用？
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Using document.getElementsByName() isn't working?
提问by user1146930
The code for the second alert command works as intended (displaying the value of the element "to", but the first alert command does not work (it's supposed to do the same thing). Why is this?
第二个警报命令的代码按预期工作（显示元素“to”的值，但第一个警报命令不起作用（它应该做同样的事情）。这是为什么？
<html>
<head>
<script type="text/javascript">
function getValue()
??{
??alert(document.getElementsByName("to").value);
alert(document.forms[0].to.value);??
??}
</script>
</head>
<body>
<form>
<input name="to" type="hidden" value="hoolah" />
<input type="button" onclick="getValue()" value="Get Value!" />
<form/>
</body>
</html>
回答by Wayne
getElementsByNamereturns an HTMLCollection. You can access the value of the first item like this:
getElementsByName返回一个HTMLCollection. 您可以像这样访问第一项的值：
document.getElementsByName("to").item(0).value
Or like this:
或者像这样：
document.getElementsByName("to")[0].value
More info:
更多信息：
回答by James Montagne
getElementsByNamereturns all elements with the given name. This means there can be more than one.
getElementsByName返回具有给定名称的所有元素。这意味着可以有多个。
If you want to get the value of the first element:
如果要获取第一个元素的值：
document.getElementsByName("to")[0].value
回答by Jeff Wooden
That's because it puts the element(s) into an array, try this example instead:
那是因为它将元素放入数组中，请尝试以下示例：
function getValues(objName)
{
var arr = new Array();
arr = document.getElementsByName(objName);
alert("total objects with name \"textfield\" = \n" + arr.length);
for(var i = 0; i < arr.length; i++)
{
var obj = document.getElementsByName(objName).item(i);
alert(obj.id + " = " + obj.value);
}
}
