Untitled

<html>
<head>
<script src="http://www.w3schools.com/lib/w3data.js"></script>
<!-- other js imports... -->
<script>
    function selectCheck(event) {
        var opt = this.options[this.selectedIndex].value;

        if (opt == "opt1"){
            //Load in html the file form.html
        }
        else{
            //Load in html the file form2.html
        }
    }

</script>
<!-- other scripts... -->
</head>

<body>


    <div class="form-group">
        <label for="exampleFormControlSelect1">Example select</label> <select
            class="form-control" id="exampleFormControlSelect" onchange="selectCheck.call(this, event)">
            <option value="opt1">option 1</option>
            <option value="opt2">option 2</option>
        </select>
    </div>
    <!-- the following lines load the html, but without any control. Here only the selected html should be loaded -->
    <div w3-include-html="html/form.html"></div>
    <div w3-include-html="html/form2.html"></div>

    <script>
    w3IncludeHTML();
    </script>

</body>