如果选择等于所选选项显示不同选择[关闭]

How could I do: if main select Value1 show First select box else if Value2 show Second select box and if Value3 show third select box

    <select id="main">
           <option value="1">Value1</option>
           <option value="2">Value2</option>
           <option value="3">Value3</option>               
    </select>
    <select id="first">
           <option value="option1">All</option>
           <option value="option2">Something</option>
    </select>

    <select id="second">
           <option value="A">One</option>
           <option value="B">Two</option>
    </select>
    <select id="third">
            <option value="White">White</option>
            <option value="Black">Black</option>
    </select>

Use the ID's as values

<select id="main">
       <option value="first">Value1</option>
       <option value="second">Value2</option>
       <option value="third">Value3</option>               
</select>

and just do:

$('#main').on('change', function() {
    $('#first, #second, #third').hide();
    $('#'+this.value).show();
});

FIDDLE

try

$('#main').on('change',function(){
    $('#first,#second,#third').hide();
    var sel = $(this).val();
    if(sel==1){
        $('#first').show();
    }else if(sel==2){
        $('#second').show();
    }else{
        $('#third').show();
    }
});

make sure #first,#second,#third are hidden at first load