Adding input elements to the DOM using jQuery

Question

I am programming a web application which accepts barcodes from a barcode reader in an input field. The user can enter as many barcodes that s/he wants to (i.e. there is no reason for a predefined limit). I have come up with a brute force method which creates a predefined number of hidden input fields and then reveals the next one in sequence as each barcode is entered. Here is the code to do this:

<form id="barcode1" name="barcode" method="Post" action="#">
    <div class="container"> 
        <label for="S1">Barcode 1 &nbsp </label>
        <input id="S1" class="bcode" type="text" name="S1" onchange="packFunction()" autofocus/>          
        <label for="S2" hidden = "hidden">Barcode 2  &nbsp </label>
        <input id="S2" class="bcode" type="text" hidden = "hidden" name="S2" onchange="packFunction()" />
        <label for="S3" hidden = "hidden">Barcode 3 &nbsp </label>
        <input id="S3" class="bcode" type="text" hidden = "hidden" name="S3" onchange="packFunction()" /> 
        <label for="S4" hidden = "hidden">Barcode 4 &nbsp </label>
        <input id="S4" class="bcode" type="text" hidden = "hidden" name="S4" onchange="packFunction()" />    
        <label for="S5" hidden = "hidden">Barcode 5 &nbsp </label>
        <input id="S5" class="bcode" type="text" hidden = "hidden" name="S5" onchange="packFunction()" />
    </div>

    <div class="submit">          
        <p><input type="submit" name="Submit" value="Submit"></p>
    </div>

</form>

<script>

$(function() {   
    $('#barcode1').find('.bcode').keypress(function(e){
        // to prevent 'enter' from submitting the form
        if ( e.which == 13 ) 
        {
            $(this).next('label').removeAttr('hidden')
                $(this).next('label').next('.bcode').removeAttr('hidden').focus();  
            return false;
        }
    }); 
});
</script>

This seems to be an inelegant solution. It would seem to be better to create a new input field after each barcode has been entered. I have tried creating new input elements in the DOM using jQuery, and I can get the new input element to show. But it uses the onchange event, which detects changes in the original input field. How do I transfer focus and detect onchange in the newly created input field? Here is the code that I have played with to test out the idea:

<div>
   <input type="text" id="barcode" class="original"/>
</div>
<div id="display">
    <div>Placeholder text</div>
</div>
<script src="./Scripts/jquery-2.2.0.min.js"></script>    
$(function () {
    $('#barcode').on('change', function () {            
        $('#display').append('<input id='bcode' class='bcode' type='text' name='S1' autofocus/>')
        });
    });
</script> 

Once I have these barcodes, I pack them into array which I then post them to a server-side script to run a mySQL query to retrieve data based on the barcodes, and then post that back to the client. So part of what I have to achieve is that each barcode that is entered into the different input fields need to be pushed into an array.

Is there an elegant way to accomplish the creation of input fields dynamically and then detecting changes in those to create yet more input fields?

Answer 1

UPDATE: I added some simple CSS to make each input field display on its own line.

Here's one strategy:

• Listen for the enter/return key on the input box.
• When the enter/return key is pressed (presumably after entering a barcode), create a new input box.
• Stop listening for the enter key on the original input and start listening for it on the new input.
• When a "submit all" button is pressed (or when tab is used to shift the focus from the most recent input to the "submit all" button and enter is pressed), then collect all the input values in an array.

$(function() {
  var finishBarcode = function(evt) {
    if (evt.which === 13) {
      $(evt.target).off("keyup");
      $("<input class='barcode' type='text'/>")
        .appendTo("#barcodes")
        .focus()
        .on("keyup", finishBarcode);
    }
  };

  var submitBarcodes = function(evt) {
    var barcodesArr = $(".barcode").map(function() {
      return $(this).val();
    }).get();
    $("#display").text("Entered Barcodes: " + barcodesArr);
  };

  var $focusedInput = $('.barcode').on("keyup", finishBarcode).focus();
  var $button = $('#submitAll').on("click", submitBarcodes);
});

input.barcode {
  display: block;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul>
  <li>Type barcode into input box</li>
  <li>To enter barcode and allow new entry, press Return</li>
  <li>To submit all barcodes, either press tab and then return or click Submit button</li>
</ul>
<div id="barcodes"><input type="text" class="barcode" /></div>
<div><button id="submitAll">Submit all barcodes</button></div>
<div id="display">Placeholder text</div>

Answer 2

If you do not display the barcodes in the html you can skip the input fields and store the read barcodes in an array[]. Not everything that happens in javascript has to be displayed in the website (View) . i do not know what code you use to scan the barcode but you do not need the input-elements at all. See the example on this site https://coderwall.com/p/s0i_xg/using-barcode-scanner-with-jquery

instead of console.log() the data from the barcode scanner can simply be saved in an array[] and be send from there.

If you want to create elements dynamcially see this thread: dynamically create element using jquery

The following code adds the p-element with the label "Hej" to the div "#contentl1"

`$("<p />", { text: "Hej" }).appendTo("#contentl1");`

Answer 3

The dynamic update you have tried out is all right. If you must push it into an array on submit you have to prevent default of form submit, serialize the form and then make an ajax request.

Heres an example:

$('form').on('submit',function(e){
    e.preventDefault();
    var formData = $(this).serializeArray();//check documentation https://api.jquery.com/serializeArray/ for more details
    $.ajax({
        type:'post',
        url:<your url>//or you could do $('form').attr('action')
        data:formData,
        success:function(){}//etc
    })
});