Javascript change input values onclick to the value on the same row which the button was clicked

问题

let's say if I select floating rate on the third row and I click on the equal sign button. The rest of the value of all the other row will change its value to floating rate. I want to apply tis function to all the other rows too.

Javascript:

<script type="text/javascript"> 
   $(document).ready(function() { 
       $('.equal').on('click', function() { 
           $('.dropDown').val('Floating Rate'); 
       }) 
   }); 
</script>

Table:

<td>
<select class="dropDown" style="width:150px" name="rate_value_1">
<option value="<?php echo $_SESSION['rate_value_1'] ;?>"><?php echo $_SESSION['rate_value_1'] ;?></option>
<option value="Fixed Rate">Fixed Rate</option>
<option value="Floating Rate">Floating Rate</option>
</select>
</td>
<td><input type="button" value="select" class="equal" /></td> 
</tr>
<tr>
<td>
<select class="dropDown" style="width:150px" name="rate_value_2">
<option value="<?php echo $_SESSION['rate_value_2'] ;?>"><?php echo $_SESSION['rate_value_2'] ;?></option>
<option value="Fixed Rate">Fixed Rate</option>
<option value="Floating Rate">Floating Rate</option>
</select>
</td>
<td><input type="button" value="select" class="equal" /></td> 
</tr>
<tr>
<td>
<select class="dropDown" style="width:150px" name="rate_value_3">
<option value="<?php echo $_SESSION['rate_value_3'] ;?>"><?php echo $_SESSION['rate_value_3'] ;?></option>
<option value="Fixed Rate">Fixed Rate</option>
<option value="Floating Rate">Floating Rate</option>
</select>
</td>
<td><input type="button" value="select" class="equal" /></td> 
</tr>
<tr>
<td>
<select class="dropDown" style="width:150px" name="rate_value_4">
<option value="<?php echo $_SESSION['rate_value_4'] ;?>"><?php echo $_SESSION['rate_value_4'] ;?></option>
<option value="Fixed Rate">Fixed Rate</option>
<option value="Floating Rate">Floating Rate</option>
</select>
</td>
<td><input type="button" value="select" class="equal" /></td> 

回答1:

in jquery,

$('.dropDown').change(function(e) {

//Here you can do you programming
  console.log(e.currentTarget);
});

for more info,

http://api.jquery.com/change/

回答2:

$("#dropDown").change(function () {
          var str = "";
          $("#dropDown option:selected").each(function () {
                str += $(this).text() + " ";
              });
          $("div").text(str);
        })

回答3:

You have a lot of problems in there. First you cannot have id="dropDown" multiple times. Use class="dropDown" instead. Second, one suggestion is to use a button instead of img.

Here is the js:

<script type="text/javascript">
   $(document).ready(function() {
       $('.equal').on('click', function() {
           $('.dropDown').val('Floating Rate');
       })
   });
</script>

And html changes:

<select class="dropDown" style="width:150px" name="rate_value_1">

<input type="button" value="select" class="equal" />

回答4:

Ok Psinyee, here is what you want, and also explained.

<script type="text/javascript">
   $(document).ready(function() {
       $('.equal').on('click', function() {
           // find coresponding dropdown
           // with select inside (this is the button ->parent is the td-> previous td)
           var crtDropdown = $('select', $(this).parent().prev('td'));
           if(crtDropdown.prop('selectedIndex') > 0) {
               // something is selected, not first option
               // change values for following selects
               // select ->parent td->parent tr->all next trs->select inside trs->set val to crtDropdown.val();
               crtDropdown.parent().parent().nextAll('tr').find('select').val(crtDropdown.val());
           }
       })
   });
</script>

<form method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>">
<table>
    <tr>
        <td>
            <select class="dropDown" style="width:150px" name="rate_value_1">
                <option value="<?php echo $_SESSION['rate_value_1'] ;?>"><?php echo $_SESSION['rate_value_1'] ;?></option>
                <option value="Fixed Rate">Fixed Rate</option>
                <option value="Floating Rate">Floating Rate</option>
            </select>
        </td>
        <td><input type="image" src="equal_button.png" class="equal" /></td> 
    </tr>
    <tr>
        <td>
            <select class="dropDown" style="width:150px" name="rate_value_2">
                <option value="<?php echo $_SESSION['rate_value_2'] ;?>"><?php echo $_SESSION['rate_value_2'] ;?></option>
                <option value="Fixed Rate">Fixed Rate</option>
                <option value="Floating Rate">Floating Rate</option>
            </select>
        </td>
        <td><input type="image" src="equal_button.png" class="equal" /></td> 
    </tr>
    <tr>
        <td>
            <select class="dropDown" style="width:150px" name="rate_value_3">
                <option value="<?php echo $_SESSION['rate_value_3'] ;?>"><?php echo $_SESSION['rate_value_3'] ;?></option>
                <option value="Fixed Rate">Fixed Rate</option>
                <option value="Floating Rate">Floating Rate</option>
            </select>
        </td>
        <td><input type="image" src="equal_button.png" class="equal" /></td> 
    </tr>
    <tr>
        <td>
            <select class="dropDown" style="width:150px" name="rate_value_4">
                <option value="<?php echo $_SESSION['rate_value_4'] ;?>"><?php echo $_SESSION['rate_value_4'] ;?></option>
                <option value="Fixed Rate">Fixed Rate</option>
                <option value="Floating Rate">Floating Rate</option>
            </select>
        </td>
        <td><input type="image" src="equal_button.png" class="equal" /></td> 
    </tr>
</table>
</form>

来源：https://stackoverflow.com/questions/10975768/javascript-change-input-values-onclick-to-the-value-on-the-same-row-which-the-bu