how to increment value in javascript with the value from the form

Question

<html>
<script>
    function remain()
    {
        var k=0;
        var rem=<?php echo $count; ?>;
        var cap=document.getElementById("cap").value;
        var k=k+cap;
        var diff=rem-cap;

        document.getElementById("demo").innerHTML = diff;

    }
</script>
</html>

<html>
<form method="post" action="list.php" target="_blank">
    Enter the capacity:
    <input type="number" name="cap" id="cap"  min=1 max=36 onchange="remain()">
    <input type="submit" id="submit" value="get seating">
</form>
</html>

My question is: in the HTML form I will enter the capacity. When I entered the capacity it will be directed to javascript and remaining strength must be show by subtracting the capacity from the total count (ex: i entered the capacity as 36 and let the count be 100).

Now the cap 36 is less from 100 and remaining 64 will be shown. But when again I entered the cap 36 it should be less from remaining 64. But this was not happening.

After calculation of `diff` you may set value of `diff` to the input you got value from: `document.getElementById("cap").value = diff;` — zmii, Aug 17 '16 at 11:56
As a side note, notice that after submitting your form, you might lose your calculation data unless you use some state persistence mechanism (cookies, server side session etc.) — Yair Nevet, Aug 17 '16 at 12:09
Why are there two `html` tags for what appears to be one document? That is not valid HTML. — Jason Cust, Aug 17 '16 at 12:56

score 2 · Answer 1 · answered Aug 17 '16 at 11:59

2

Something like this?? Click the geat seating button after mentioning the capacity.

var rem = 100

function remain() {
  var k = 0;
  var cap = document.getElementById("cap").value;
  var k = k + cap;
  rem = rem - cap;

  document.getElementById("demo").innerHTML = rem;
}

<form method="post" action="list.php" target="_blank">
  Enter the capacity:
  <input type="number" name="cap" id="cap" min=1 max=36>
  <input onclick="remain()" type="submit" id="submit" value="get seating">
</form>
<div id="demo"></div>

answered Aug 17 '16 at 11:59

Pugazh

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@PavanKumar : What value do you expect ? – Pugazh Aug 17 '16 at 14:41
thank u thank u very much its works very nice. exactly what i want. thank u my friend – Pavan Kumar Aug 17 '16 at 15:50
another question friend how can i send the value rem in javascript to a variable in php – Pavan Kumar Aug 18 '16 at 06:10
@PavanKumar : Check this link - http://stackoverflow.com/questions/9789283/how-to-get-javascript-variable-value-in-php – Pugazh Aug 18 '16 at 06:57
its not working properly. my intention is when the rem=0 the form to enter the capacity must be disabled. please help me – Pavan Kumar Aug 18 '16 at 09:23

how to increment value in javascript with the value from the form

1 Answers1