有两个同名的输入元素是否有效？

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Yes.

More, it is essential if you are dealing with radio button groups.

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Yes -- each will only submit with their respective forms.

If you have them in the same form, one will override the other and it is not valid.

EDIT: As pointed out by Mahmoodvcs that the overriding only occurs in some languages (such as PHP) as is not inherent within HTML itself.

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最佳答案

Yes, it is valid

This is Good

<form name="form1">
<input type="hidden" name="url" value="1">
</form>


<form name="form2">
<input type="hidden" name="url" value="2">
</form>

This is also fine and will generally be interpreted as an array of values, e.g. {url: [1, 2]}, depending on what your server does. In a URL encoding, it will look like url=1&url=2.

<form name="form1">
<input type="hidden" name="url" value="1">
<input type="hidden" name="url" value="2">
</form>

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To test if it is valid or not, creat you page and test at W3C here :

http://validator.w3.org/

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"This is Not Good" parses correctly on every browser I know of; if two url's appear in the url encoded string, it will be treated as an array. Try this in JQuery:

$('<form name="form1">\
<input type="hidden" name="url" value="1">\
<input type="hidden" name="url" value="2">\
</form>').serialize()

and you will get: "url=1&url=2"

a well-written query string parser will return a json structure like this:

 {"url":["1", "2"]}

Is it strictly spec? Nope, but neither is creating a multi-line string by escaping the EOL with a backslash, as I did above.

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A) Your first example is okay, because the forms time of submission will be different:

<form id="1">
<input type="hidden" name="url" value="1">
</form>
<form id="2">
<input type="hidden" name="url" value="2">
</form>

B) Your second example is also okay, but not standard coding practice:

<form>
<input type="hidden" name="url" value="1">
<input type="hidden" name="url" value="2">
</form>

Java code two extract both values:

Map<String,String[]> parmMap = requestObj.getParameterMap();
String input1 = parmMap.get("url")[0];
String input2 = parmMap.get("url")[1];

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<form>
<input type="hidden" name="url[]" value="1">
<input type="hidden" name="url[]" value="2">
</form>

In PHP you will get values with $_POST['url']

for($i=0;$i<count(url);$i++)
echo $_POST['url'][$i];