jquery只显示所选选项之一+必需

$(document).ready(function(){ $('#problem').on('change', function(){ $('.display, .display_1').show(); if (this.value.trim()) { if (this.value !== 'test') { $('.display').hide(); } if (this.value !== 'test1') { $('.display_1').hide(); } } }); });

我清理了html并添加了一些css。基本上这是一个简单的 if 根据select语句的值显示一个或另一个输入字段的语句:

$(document).ready(function(){

    $("#problem").on("change", function(){
        $(".input.text").hide();
        $(".input.text input").removeAttr("required");
        if(this.value === "test"){
            $(".input.text#router").show();
            $(".input.text#router input").prop("required", true);
        }else if(this.value === "test1"){
            $(".input.text#switch").show();
            $(".input.text#switch input").prop("required", true);
        }
    });
});

form .input{
   display: flex;
   margin-bottom: 10px;
}

form .input input, form .input select{
   margin-left: 20px;
}

form .input.text{
    display: none;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.1/jquery.min.js"></script>
<form id="e">
    <div class="input">
        <span>Problem:</span>
        <select required id="problem" name="problem">
            <option value=""></option>
            <option value="test">test</option>		
            <option value="test1">test1 </option>
         </select>
    </div>
    <div class="input text" id="router">
        <span>Router</span>
        <input id="router" name="router" type="text" maxlength="50" size="50">
    </div>
    <div class="input text" id="switch">
        <span>Switch</span>
        <input id="switch" name="switch" type="text" maxlength="50" size="50">
    </div>
    <input type="submit"  class="submit" value="submit">
</form>