Wrapping div inside an if condition - php

Question

So, I have the following div and I want to show it just if the item type is equal to "Mobile Phone" or Tablet, selected on the same page with a combo box (also an input but instead of writing it's a combobox), but I just can't figure it out how to wrap this div inside an if condition based on what is selected on the combo box, can anyone help me?
Something like this:
if item = "MobilePhone" or item = "Tablet" --------> Show div
But I have Php code already inside the div.. that's why i just can't do it
<div class="control-group <?php echo !empty($imeiError)?'error':'';?>">
<label class="control-label"><strong>IMEI</strong></label>
<div class="controls">
<input name="imei" type="text" placeholder="IMEI" value="<?php echo !empty($imei)?$imei:'';?>">
<?php if (!empty($imeiError)): ?>
<span class="help-inline"><?php echo $imeiError;?></span>
<?php endif;?>
</div>
</div>
And that's how i select the input that I want
<div class="control-group <?php echo !empty($itemError)?'error':'';?>">
<label class="control-label"><strong>Item</strong></label>
<div class="controls">
<select name="item">
<option value="MobilePhone" <?php echo !empty($item) && $item == 'MobilePhone' ? 'selected' : ''; ?>>MobilePhone</option>
<option value="Tablet" <?php echo !empty($item) && $item == 'Tablet' ? 'selected' : ''; ?>>Tablet</option>
<option value="Computer" <?php echo !empty($item) && $item == 'Computer' ? 'selected' : ''; ?>>Computer</option>
<option value="HeadPhones" <?php echo !empty($item) && $item == 'HeadPhones' ? 'selected' : ''; ?>>HeadPhones</option>
</select>
</div>

Answer 1

You already seem to be checking for $item in your second code, so assuming that $item is set you can use this code to show the div only if "MobilePhone" or "Tablet" is selected:
<?php if ($item == "MobilePhone" || $item == "Tablet") : ?>
<div class="control-group <?php echo !empty($imeiError)?'error':'';?>">
<label class="control-label"><strong>IMEI</strong></label>
<div class="controls">
<input name="imei" type="text" placeholder="IMEI" value="<?php echo !empty($imei)?$imei:'';?>">
<?php if (!empty($imeiError)): ?>
<span class="help-inline"><?php echo $imeiError;?></span>
<?php endif;?>
</div>
</div>
<?php endif ?>

Answer 2

If your div has display:none in your css.
Use select's onchange="myFunc()"
And in your myFunc() look for selected value and do whatever you want.
document.getElementById('yourDivId').style='display:block' sets your div visibility.
<select onchange="myFunction()" id="select"><!--selections with different values --></select>
<script> function myFunction() {
var selected=document.getElementById("select").value;
if(selected=="Mobile")
document.getElementById("yourDivId").style="display:block"; }
</script>

Answer 3

you can use a variable $html to organize html in if condition like below code.
<?php
$item = "MobilePhone";
$html = "";
if ($item == "MobilePhone" || $item == "Tablet") {
$html .= '<div class="control-group';
echo !empty($imeiError)?'error':'';
$html .= '<label class="control-label"><strong>IMEI</strong></label><div class="controls">
<input name="imei" type="text" placeholder="IMEI" value="'.!empty($imei)?$imei:''; '">';
if (!empty($imeiError)):
$html .= '<span class="help-inline">';
echo $imeiError;
$html .= '</span>';
endif;
$html .='</div></div>';
}
?>