从html表单到javascript

Question

I have a form that requires three inputs as follows:

  <form>
    <input name="mn" 
           type="number"
           min="1"
           value="1">
    <input name="mx" 
           type="number"
           min="2"
           value="10">
    <input name="step" 
           type="number"
           min="1"
           value="1">
    <input onclick="myfunc()"
           type="submit"
           value="calculate">
  </form>

all i require is to be able to access the three fields directly in javascript. I do not need to pass the information anywhere else.

Could anyone point me in the right direction? I have read examples where there has been one input, but not multiple.

  <script type="text/javascript">
    function myfunc() {
    var mn = document.getElementsByName("mn")
    var mx = document.getElementsByName("mx")
    var step = document.getElementsByName("step")
    alert((mn + mx) / step)
    }
  </script>

Answer 1

Give your form an id like so

<form id="myForm">

The other thing to watch out for is that the is that the value attribute is a string so adding the two values concatenates them rather than summing them.

Try instead

var frm = document.forms["myForm"];

var _mn = parseInt( frm["mn"].value );
var _mx = parseInt( frm["mx"].value );
var _step = parseInt( frm["step"].value );

var result = ( _mn + _mx ) / _step;

Answer 2

I'd start with giving each input an id then i could use:

var min = document.getElementById('mn')

and so on. To access the value you simply would call

min.value

Also there is no point in removing the i from min and the a from max. That is not optimized just hard to read and understand.

Answer 3

if u need to access to the values of the inputs change your code to:

function myfunc() {
  var mn = document.getElementsByName("mn")[0];
  var mx = document.getElementsByName("mx")[0];
  var step = document.getElementsByName("step")[0];
  // you may need to validate your values here, like step.value != 0
  alert((mn.value + mx.value) / step.value)
}

Answer 4

Try this:

  <script type="text/javascript">
    function myfunc() {
    var mn = document.getElementsByName("mn")[0].value;
    var mx = document.getElementsByName("mx")[0].value;
    var step = document.getElementsByName("step")[0].value;
    var top = mn / mx;
    alert(top / step);
    }
  </script>