Calculator in javascript. on submit value flashes and disappears. :(

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<html>
<head>
<title>Form Validation</title>
<script type="text/javascript">
function calculate()
{
var x=eval(document.getElementById("txt_area").value);
document.getElementById("txt_area").value = x;
}
function display(clicked_id)
{
    var pre = document.getElementById("txt_area").value;

    pre= pre + document.getElementById(clicked_id).value;

    document.getElementById("txt_area").value=pre;

}
</script>
</head>
<body>
         <form action="" name="myForm">
                 <table border="1">
                     <tr>
                       <td align="right"><input type="text name="text" id="txt_area"/></td>
                     </tr>
                     <tr>
                       <td align="right"> <input type="button" onclick="display(this.id)" id="1" value="1"/><input name="2" onclick="display(this.id)" id="2" type="button" value="2"/><input name="3" onclick="display(this.id)" id="3" type="button" value="3"/><input onclick="display(this.id)" id="+" type="button" value="+"/></td>
                     </tr>
                     <tr>
                       <td align="right"><input type="button" id="4" onclick="display(this.id)" value="4"/><input type="button" onclick="display(this.id)" id="5" name="5" value="5"/><input name="6" onclick="display(this.id)" id="6" type="button" value="6"/><input onclick="display(this.id)" id="-" type="button" value="-"/></td>
                     </tr>
                     <tr>
                        <td align="right"><input type="button" onclick="display(this.id)" id="7" value="7"/><input type="button" onclick="display(this.id)" id="8" value="8"/><input onclick="display(this.id)" id="9" type="button" value="9"/><input onclick="display(this.id)" id="*" type="button" value="*"/></td>
                     </tr>
                     <tr>
                         <td align="right"><input type="submit" value="Submit" onClick="calculate()"/></td>
                     </tr>
                </table>

         </form>

 </body>
 </html>

Posted 13-Oct-13 20:42pm

Dhirendra Panwar

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2 solutions

Solution 2

just chnaged the buttons type from SUBMIT to BUTTON. that helped too.

Thanks "Azee".

Posted 14-Oct-13 19:41pm

Dhirendra Panwar

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**Azee** · Accepted Answer · 2013-10-13T21:29:00

Hey there,

You need to prevent the Button's PostBack after it has calculated and set the answer, do this:

Replace your Submit button with this:

HTML

<input type="submit" value="Submit"  önclick="return calculate();" />

and add a return false at the end of calculate() function:

JavaScript

function calculate() {
            var x = eval(document.getElementById("txt_area").value);
            document.getElementById("txt_area").value = x;
            return false;
        }

Let me know if it helps.

Azee...