1.先引入包select2

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<script src="jquery.min.js?v=2.1.4"></script>
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<script src="select2/js/select2.js"></script>
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<script src="select2/js/pinyin.js"></script>
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<script src="select2/js/i18n/zh-CN.js"></script>

2.配置，举例：

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 <select name="cid" class="form-control channel" required="" aria-required="true">
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 {foreach name='channeles' item='channels' }
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  <option value="{$channels.id}"  >{$channels.channel}</option>
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 {/foreach}
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</select>
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<script type="text/java script">
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  $(".channel").select2({
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            placeholder: "请选择",
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            allowClear: true,
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            language: "zh-CN",
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   });
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</script>