JSFiddle - React, Tailwind, and code Playground

HTML

<div class="input string optional">
    <label for="company_navn" class="string optional"> Name</label>
    <input type="text" size="50" name="company[navn]" maxlength="255" id="webhost_navn" class="string optional">
</div>
<div id='redDiv' style="width:30px;height:30px;margin-top:10px;display:block;background:green;"></div>
<div id='greenDiv' style="width:30px;height:30px;margin-top:10px;display:block;background:red;"></div>

CSS

label {display:block;}

JavaScript

$('#redDiv').click(function() {
    $('#webhost_navn').data('myData', 'i');
    alert('Value of myData: ' + $('#webhost_navn').data('myData'));
});
$('#greenDiv').click(function() {
    $('#webhost_navn').data('myData', null);
    alert('Value of myData: ' + $('#webhost_navn').data('myData'));
});