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Editorial Team
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Asked: 2026-05-19T14:35:07+00:00

Suposse user hits SPACE in a text -field. I want to check the value

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  1. Suposse user hits SPACE in a text -field. I want to check the value in the select -box. I use input.addEventListener('keydown', function(e)... to track the SPACE-hitting-point but how can I get the value of the select block <select id='topic'><option value="hello"></option> ...</section>?

  2. How can you stdout the value of the selected index? Cannot understand why not below.

        var el = document.getElementById("topic");
    var topicValue = el.options[el.selectedIndex].value;

    // PROBLEM: Won't do anything (despite inside <script> -tags)
    window.alert(topicValue);

where the topic is the select <select id="topic"[^>]*>[^<]*</select>.

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1 Answer

  1. Editorial Team

    The events work in the select, not to options but just conditional to the script.

    <html>
<body>

<script>
        function alertMe(option){
                if(option == "saab"){
                        window.alert("you clicked saab in selec!");
                        document.getElementById("txt").value='saab!';
                }
        }
</script>


<select onChange="alertMe(this.value);">
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
  <option value="m"> Mercedes</option>
  <option>Audi</option>
</select>

<input type="text" id="txt" value="change me"></input>

</body>
</html>

    [Answers to the updated]

    1. You can access the select with document.getElementById('topic').options.selectedIndex or mySelect.options[selectedIndex].value (does not work with me). And apparently you could create a form to which you could refer by document.forms['topic'].elements[id] but not sure about this one. More.
    2. @Kosh that is irritating! Just do a dictionary = {0:"topic", 1:"hello",...,n:"topic_{n}"} and then use the getElementById('topic').selectedId as a key and forget the values. Not solved but rounded.

    [Update] I think I solved it, just el.value, no selectedIndex needed:

    <html>
<body>

<script>

function printSelectValue()
{
        var el = document.getElementById("selectOne");
        alert(el.value);

}
</script>


<select id="selectOne" onChange="printSelectValue()"> 
<option value="volvo">Volvo</option>
<option value="saab">Saab</option>
<option value="m"> Mercedes</option>
</select>

</body>
</html>
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