javascript - Calculator form alternative -

i have current code below, working. problem code in form , can't have nested forms. how change code, works div parent element instead of form?

<form> <script type="text/javascript">    function inmet(form){        form.in2met.value = ((form.inch.value -0) * 25.4).tofixed(2)    } </script> <div id="calcbody">     <div class="calctitle">convert <br />inches millimetres</div>     <div class="singcalcquestion">enter inches:          <input class="box1" type="text" name="inch" />     </div>     <div class="singsubmit">          <input onclick="inmet(this.form)" type="button" value="go" />          </div>     <div class="singcalcanswer">equals in millimetres:<br />          <input class="calcbox2" type="text" readonly="readonly" name="in2met" />     </div> </div> </form> 

one option use element.getelementsbyclassname() or similar method input field want:

<div id="form-root">   <script type="text/javascript">   function inmet(calcroot){     calcroot.getelementsbyclassname('calcbox2')[0].value = ((form.inch.value -0) * 25.4).tofixed(2);   }   // example: inmet(document.getelementbyid('form-root'))   </script>   <div id="calcbody">     <div class="calctitle">convert <br />inches millimetres</div>     <div class="singcalcquestion">enter inches: <input class="box1" type="text" name="inch" /></div>     <div class="singsubmit"><input onclick="inmet(document.getelementbyid('form-root'))" type="button" value="go" /></div>     <div class="singcalcanswer">equals in millimetres:<br /><input class="calcbox2" type="text" readonly="readonly" name="in2met" /></div>   </div> </div>