可以添加自定义的Select控件

1.控件dom

<select name="WebSiteTarget" id="WebSiteTarget" class="w1" onchange="editable2(this);"><option value="-1">请选择城市</option><option>福州</option><option>厦门</option><option>南平</option><option value="0">(自定义输入)</option>
</select>

2.脚本

<script>function editable2(dom) {if (dom.value == "0") {var newvalue = prompt("请输入", "");if (newvalue) {addSelected(dom, newvalue, newvalue);}}}function addSelected(fld1, value1, text1) {if (document.all) {var Opt = fld1.document.createElement("OPTION");Opt.text = text1;Opt.value = value1;fld1.options.add(Opt);Opt.selected = true;} else {var Opt = new Option(text1, value1, false, false);Opt.selected = true;fld1.options[fld1.options.length] = Opt;}}
</script>

3.效果