How to pass a form element value to the onclick event?

Question

I am trying to write an iPhone app and on one of my pages and I want to capture the form data and then using the onclick event to pass the values to a JavaScript function which will open the SMS window.

The onclick event below passes txt1 and txt2 to the JavaScript function and works perfectly.

<input onclick="window.plugins.smsComposer.showSMSComposer('txt1', txt2');" type="button" value="Send Reboot Command Via SMS" />

However, I need to replace txt1 and txt2 with the actual values the user enters in the form.

The following is the code for the page hope it assist to understand what I am trying to achieve.

JavaScript code to capture the form field values:

function updateTxt(field,toField){
    var field = document.getElementById(field);
    var toField = document.getElementById(toField);
    toField.innerHTML=field.value;
}

HTML Page Code:

<div data-role="page" id="DevicesConfigurePage" data-add-back-btn="true">
  <div data-role="header" id="myheader" data-position="fixed">
    <h1>Reeboot</h1>
  </div>
<br>              
<input type="text" id="box1" onkeyup="updateTxt('box1','txt1');"><br>
<input type="text" id="box2" onkeyup="updateTxt('box2','txt2');"><br>
<input type="text" id="box3" onkeyup="updateTxt('box3','txt3');"><br>
<input type="text" id="box4" onkeyup="updateTxt('box4','txt4');"><br>

<input onclick="window.plugins.smsComposer.showSMSComposer(id="txt1", id="txt2");" type="button" value="Send Reboot Command Via SMS" /><br />                            <br>
<!-- /content --> 
<p class="copyright">Copyright &copy; TrackingCentral Pty Ltd</p>
</div><!-- /page -->

Answer 1

I don't see any relation between the jQuery and HTML code you provided. (Before you eidt your post further). I think you want to place a specific value in some specific region. You may try this.

$('#toField').html(field.value);

Instead of

toField.innerHTML=field.value;

and also fix this:

var field = document.getElementById('field');
var toField = document.getElementById('toField');