I have some text box, for example 4 inputs, I want to append each value to one certain text box with comma on KeyUp function beside default value but problem is it will overwrite value with previous value.

want something like this:

> 
> 01115468852, 234324234, 423423113345, 43341889955
> 
> 
> 

```js
var curval = $('#PhoneTextbox').val();

$('.tag').each(function() {
  $(this).keyup(function() {
    var tags = $(this).val();
    $('#PhoneTextbox').attr('value', curval + " , " + tags);
  });
});
```

```html
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.0.0/jquery.min.js"></script>
<input id="PhoneTextbox" value="01115468852" type="text" />
<br />
<br />
<br />
<input class="tag" value="" type="text" />
<input class="tag" value="" type="text" />
<input class="tag" value="" type="text" />
<input class="tag" value="" type="text" />
```