动态设置select默认显示值

<select id="input_select" type="number" >
    <option value="1">1</option>
    <option value="2">2</option>
    <option value="3">3</option>
    <option value="4">4</option>
    <option value="5">5</option>
</select>

//js
var _input =3;//从后台获取的值
$("#input_select option[value='"+_input +"']").attr('selected','selected');