根据使用javascript或PHP的输入自动减去没有按钮点击的数字

Question

I have more than 2 inputs that can only accept numbers and there is a displayed number on the top. How could I subtract the numbers that I have entered just by changing the value on any of the input boxes? Please Help.

 <p id='Answer'> 100 </p>
 <input type='number' max='10' min='0' name='num1'>
 <input type='number' max='5' min='0' name='num2'>

Answer 1

Ok your question is a little ambiguous. Anyway I have assumed you want the following. You want the num1 to subtract automatically from num2 and be displayed in id='Answer'.

Following is the code to that in jQuery.

$(".sub").focusout(function() {
  $("#answer").html('');
  var num1 = $("#num1").val();
  var num2 = $("#num2").val();
  var answer = num1 - num2;
  $("#answer").html(answer);
});

You can view the demo here

In case you want both input fields to subtract from 100. Following is the code.

$(".sub").focusout(function() {
$("#answer").html('');
var num1 = $("#num1").val();
var num2 = $("#num2").val();
var answer = 100 - num1 - num2;
$("#answer").html(answer);
});

And following is the link to demo

Based on your question in last comment. Download jquery from here. Now include the downloaded script in your header. Or just use the following code.

<script src="//code.jquery.com/jquery-1.11.0.min.js"></script>

After you have included jquery you need to use your .focusout code like stated below

<script type="text/javascript">
$(document).ready(function() {
   $(".sub").focusout(function() {
     $("#answer").html('');
     var num1 = $("#num1").val();
     var num2 = $("#num2").val();
     var answer = 100 - num1 - num2;
     $("#answer").html(answer);
    });
});
</script>