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Editorial Team
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Asked: 2026-06-12T00:03:36+00:00

I am trying to make a simple calculator wher a person would in put

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I am trying to make a simple calculator wher a person would in put two values and then when clicking a button an alert box would give the result. But it is not working.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<script type="text/javascript">

<!--//onclick handler //-->
function gonum()
{
var input1=document.getElementById('a').value;
var operator=document.getElementById('op').value;
var input2=document.getElementById('b').value;


    if (operator=="+")
    {
        add(input1,input2);
    }
}


function add(input1,input2)
{
    alert(input1+input2);
}


</script>
</head>
<body>
<form>
<input type="text" name="a"/>
<input type="text" name="op"/>
<input type="text" name="b"/>
<input type="button" value="=" name="btn" onClick="gonum()" />
</form>
</body>
</html>
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1 Answer

  1. Editorial Team

    One glaring issue that I see is this:

    var input1=document.getElementById('a').value;
var operator=document.getElementById('op').value;
var input2=document.getElementById('b').value;

    Combined with this:

    <input type="text" name="a"/>
<input type="text" name="op"/>
<input type="text" name="b"/>

    Observe that you aren’t assigning any IDs to the input elements; however, your JavaScript is attempting to call them by their (non-existent) id.

    Change your html to this and you should be golden:

    <input type="text" name="a" id="a"/>
<input type="text" name="op" id="op"/>
<input type="text" name="b" id="b"/>
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