It is showing null value

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I have been practicing javascript and i am not able to display the value .It keeps showing null.

What I have tried:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
 
</head>
<body>
 
    <h1>testing dom </h1>
        name <input type="text">
        number <input type="number" id="number" value="000">
        <button onclick="clicked()">submit</button>
        

  

   
    <script>
        
        function clicked()
        {
            document.write("submit clicked");
            var a = document.getElementById("number").value;
            document.write(a);
         
        }
</script>
</body>
</html>

Posted 22-Nov-21 4:06am

Jatin Gupta 2021

Updated 19-May-22 18:56pm

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Richard Deeming · Answer 1 · 2021-11-22T04:30:00

Document.write() - Web APIs | MDN[^]:
Note: Because document.write() writes to the document stream, calling document.write() on a closed (loaded) document automatically calls document.open(), which will clear the document.

Your first call to document.write clears the document, so there is no element to find.

Either read the value before calling document.write:

JavaScript

function clicked()
{
    var a = document.getElementById("number").value;
    document.write("submit clicked");
    document.write(a);
}

or display the output in some other way - eg: in the developer console[^]:

JavaScript

function clicked()
{
    console.log("submit clicked");
    var a = document.getElementById("number").value;
    console.log(a);
}

OriginalGriff · Answer 2 · 2021-11-22T04:33:00

Document.Write clears the existing HTML and replaces it with a blank page.
So when you call it to display "submit clicked" the subsequent call to getElementById fails because the HTML no longer contains and such element.

Try this:

JavaScript

function clicked()
{
    var a = document.getElementById("number").value;
    document.write("submit clicked");
    document.write(a);
}

Richard MacCutchan · Answer 3 · 2021-11-22T04:34:00

I think your example code is incorrect, the first call to document.write rewrites the entire page so the next line in your script does not find an element with the id "number". If you remove that line it will (sort of) work. However, I would suggest working through the JavaScript Tutorial[^] for better samples.

It is showing null value

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