如何自動選擇jquery

Question

這個請求可能會讓你有點傻。

選擇1

<select id="select1" name="s1"> 
    <option id="1" value="Facebook and Twitter">Value 1</option> 
    <option id="2" value="Google and Yandex">Value 2</option> 
    . 
    . 
    . 
</select> 

選擇2

<select id="select2" name="s1"> 
    <option id="1" value="Okay">Value 1</option> 
    <option id="2" value="No">Value 2</option> 
    . 
    . 
    . 
</select> 

選擇Facebook和Twitter時，如何選擇好？

Answer 1

首先dropdwon的名字和id都是一樣的，使它不同。您可以選擇一個下拉菜單，如：

$('#selectId').val(2); 

它將使下拉選項的值爲2。

$(document).ready(function(){ 
 
    $('#select2').val('No'); 
 
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 
 

 
<select name="s2" id="select2"> 
 
    <option value="Okay">Value 1</option> 
 
    <option value="No">Value 2</option> 
 
</select>

例如：它將使下拉Value 2即No作爲選擇

Answer 2

：ID必須是唯一的..所以用類代替不重複ID

2nd：你需要.change()事件selest 1並獲取其.val()

：與價值比較這.val()你Facebook和Twitter

第四：你需要prop("selected" , true)好從select 2或只是使用.val('Okay')

$(document).ready(function(){ 
 
    $('#select1').on('change', function(){ 
 
    var ThisVal = $(this).val(); 
 
    if(ThisVal == "Facebook and Twitter"){ 
 
     $('#select2').val('Okay'); 
 
    } 
 
    }); 
 
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 
 
<select name="s1" id="select1"> 
 
    <option value="Facebook and Twitter">Facebook and Twitter</option> 
 
    <option value="Google and Yandex">Google and Yandex</option> 
 
</select> 
 
<select name="s2" id="select2"> 
 
    <option value="Okay">Okay</option> 
 
    <option value="No">No</option> 
 
</select>

Answer 3

1）Id attribute應該是每個元素

2）使用上change事件獲得的第一select的current value獨特的，如果它Facebook and Twitter然後選擇在第二okay否則選擇No這樣

$(document).ready(function(){ 
 
    $('#select2').val('No'); 
 
}); 
 

 
$(document).on('change','#select1',function(){ 
 

 
    if($(this).val()=='Facebook and Twitter'){ 
 
    
 
    $('#select2').val('Okay'); 
 
    
 
    }else{ 
 
    
 
    $('#select2').val('No'); 
 
    } 
 

 
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 
 

 
<select name="s1" id="select1"> 
 
    <option value="">select</option> 
 
    <option value="Facebook and Twitter">Value 1</option> 
 
    <option value="Google and Yandex">Value 2</option> 
 
</select> 
 
<select name="s2" id="select2"> 
 
    <option value="">select</option> 
 
    <option value="Okay">Value 1</option> 
 
    <option value="No">Value 2</option> 
 
</select>

Answer 4

你可以試試這個

$(document).ready(function(){ 
 
if($("[name='s1']").val() == "Facebook and Twitter"){ 
 
     $('#select2 option[value=Okay]').attr('selected','selected'); 
 
    } 
 
    
 
    $("[name='s1']").change(function(){ 
 
    if($(this).val() == "Facebook and Twitter"){ 
 
     $('#select2 option[value=Okay]').attr('selected','selected'); 
 
    } 
 
    else{ 
 
     $('#select2 option[value=No]').attr('selected','selected'); 
 
    } 
 
    }); 
 
})

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 
 
<select name="s1"> 
 
    <option value="">Select</option> 
 
    <option id="1" value="Facebook and Twitter">Value 1</option> 
 
    <option id="2" value="Google and Yandex">Value 2</option> 
 

 
</select> 
 
<select name="s2" id="select2"> 
 
    <option value="">Select</option> 
 
    <option value="Okay">Value 1</option> 
 
    <option value="No">Value 2</option> 
 
</select>