JavaScript get element by name

Question

JavaScript get element by name

Rozważmy tę funkcję:

function validate()
{
  var acc = document.getElementsByName('acc').value;
  var pass = document.getElementsByName('pass').value;

  alert (acc);
}

I ta część HTML:

<table border="0" cellpadding="2" cellspacing="0" valign="top">
    <tr>
        <td class="td1">Account</td>
        <td class="td2"><input type="text" name="acc" /></td>
    </tr>
    <tr class="td1">
        <td>Password</td>
        <td class="td2"><input type="password" name="pass" /></td>
    </tr>
</table>
<div><button onClick="validate()" class="cupid-greenx">Login now</button></div>

Okno alertu jest wyświetlane, ale pokazuje "undefined".

109

javascript html dom

Author: Brett DeWoody, 2012-04-25

Source

5 answers

Zwróć uwagę na liczbę mnogą w tej metodzie:

document.getElementsByName()

, który zwraca tablicę elementów, więc użyj [0], aby uzyskać pierwsze wystąpienie, np.

document.getElementsByName()[0]

22

Author: Ozzy,
Warning: date(): Invalid date.timezone value 'Europe/Kyiv', we selected the timezone 'UTC' for now. in /var/www/agent_stack/data/www/doraprojects.net/template/agent.layouts/content.php on line 54
2012-04-24 21:21:12

Chcesz tego:

function validate() {
    var acc = document.getElementsByName('acc')[0].value;
    var pass = document.getElementsByName('pass')[0].value;

    alert (acc);
}

9

Author: Elliot Bonneville,
Warning: date(): Invalid date.timezone value 'Europe/Kyiv', we selected the timezone 'UTC' for now. in /var/www/agent_stack/data/www/doraprojects.net/template/agent.layouts/content.php on line 54
2012-04-24 21:20:23

document.getElementsByName("myInput")[0].value;

5

Author: Sam Battat,
Warning: date(): Invalid date.timezone value 'Europe/Kyiv', we selected the timezone 'UTC' for now. in /var/www/agent_stack/data/www/doraprojects.net/template/agent.layouts/content.php on line 54
2012-04-24 21:20:47

Dokument metody.getElementsByName zwraca tablicę elementów. Na przykład powinieneś wybrać najpierw.

document.getElementsByName('acc')[0].value

5

Author: dalazx,
Warning: date(): Invalid date.timezone value 'Europe/Kyiv', we selected the timezone 'UTC' for now. in /var/www/agent_stack/data/www/doraprojects.net/template/agent.layouts/content.php on line 54
2012-04-24 21:21:38

score 199 · Accepted Answer

document.getElementsByName zwraca NodeList elementów, więc nie ma właściwości .value. stąd ten niezdefiniowany błąd, który widzisz.

What you want is document.getElementsByName("acc")[0].value

199

Author: Aidanc,
Warning: date(): Invalid date.timezone value 'Europe/Kyiv', we selected the timezone 'UTC' for now. in /var/www/agent_stack/data/www/doraprojects.net/template/agent.layouts/content.php on line 54
2016-05-20 11:13:06