Multi-line string insert using jQuery

a cleaner approach is to use <script> tag

https://stackoverflow.com/a/12097933/1416458

<script id="stuff_you_want" type="text/plain">
<tr>
    <td><input type="text" class="optionField" value="Options" /></td>
    <td>
        <ul class="option">
            <li><select><option>Value..</option></select></li>
        </ul>
    </td>
</tr>
</script>

<script>

    // pure javascript
    var text = document.getElementById("stuff_you_want").innerHTML ;

    //or using jQuery... (document ready for safety)
    $(document).ready(function() {

        var text = $("#stuff_you_want").html(); 

    }

</script>

content-type must be set for html 4.0 compliance.

Change all the double quotes for the attributes to single quotes.

$("#addSelect").click(function() { 
        $("#optionsForm").after("<tr> \
    <td><input type='text' class='optionField' value='Options' /></td> \
    <td> \
        <ul class='option'> \
            <li><select><option>Value..</option></select></li> \
        </ul> \
    </td> \
</tr>"); 
} );