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Editorial Team
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Asked: 2026-05-24T12:20:49+00:00

I am having problem with this error: ‘undefined’ is null or not an object’

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I am having problem with this error:

‘undefined’ is null or not an object’

Can you please have a look and let me know. In my coding, I want to have simple DOM JavaScript code

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
</head>
<script>
    init();
    function init()
    {
        getElementByTabIndex("4", "submit")[0].addEventListener("click", Verify, false);
    }
    function Verify() {
        alert('done');  
        // all verification code will be here...
    }
    function getElementByTabIndex(index, type, node)
    {
        if (!node)
        { 
            node = document.getElementsByTagName('body')[0]; 
        } 

        var a = [];
        els = node.getElementsByTagName('*'); 
        for (var i = 0, j = els.length; i < j; i++) 
        { 
            if (els[i].tabIndex == index && els[i].type == type)
            { 
                a.push(els[i]);
            } 
        } 
    return a; 
}

</script>
<body>
<input type="email" id="email" /><input type="password" id="pass" /> <label class="Login" for="login"><input value="Log In" tabindex="4" type="submit" id="login"></label>
</body>
</html>
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1 Answer

  1. Editorial Team

    You have to move you code at bottom or call init() after body is loaded.

    Reason: you are trying to get elements even before they exists.

    Eg : 

    <head>
   <script>
      var elm= document.getElementById('id');

      //this will be always undefied, as trying to read element even before they exist
   </script>
</head>

<body>
  <div id='foo'></div>

   <script>
      var elm= document.getElementById('id');

      //this wont be undefined 
   </script>

</body>
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