JSFiddle - React, Tailwind, and code Playground

HTML

<div class="dropdown" data-bsselect="false" id="DefinedValueParam">
    <button class="btn" data-toggle="dropdown"><span>This is a long value which has been truncated  </span><b class="caret"></b></button>
    <ul class="dropdown-menu">
        <li><a data-value="" data-selected="true">No Value <i class="icon-ok"></i></a></li>
        <li><a data-selected="false" data-value="1">Value 1 <i class=""></i></a></li>
        <li><a data-value="2" data-selected="false">Value 2 <i class=""></i></a></li>
        <li><a data-value="3" data-selected="false">Value 3 <i></i></a></li>
    </ul>
</div>

CSS

@import url('http://twitter.github.com/bootstrap/assets/css/bootstrap.css');

* {
    line-height:14px;
    font-size:11px;
}

.btn {
    line-height:14px;
    min-width:125px;
    max-width:125px;
    border-radius:0px;
    font-size:11px;
}

button.btn span {
    min-width:91px;
    max-width:91px;
    overflow:hidden;
    white-space:nowrap;
    -ms-text-overflow: ellipsis;
    -o-text-overflow: ellipsis;
    text-overflow: ellipsis;
    float:left;
}

.btn .caret {
    margin-top:4px;
}