Adding validation rule(s) depending on option selected from dropdown menu

问题

I am using the jquery validate plugin for the first time. I am in a situation where I have a select box that has three options. I need to do two things:

1. Make the select box required.
2. Depending on the option selected, make other text boxes required.

So...

<select id="selectBox">
    <option value selected></option>
    <option value="1">1</option>
    <option value="2">2</option>
    <option Value="3">3</option>
</select>

Coord 1: <input type="text" name="coord1"><br>
Coord 2: <input type="text" name="coord2"><br>
Coord 3: <input type="text" name="coord3"><br>

• If option 1 is selected on the dropdown, Coord 1 is required.
• If option 2 is selected, Coords 1 and 2 are required.
• If option 3 is selected, Coord 1 and Coord 3 are required.

How does this work adding custom rules to the validator?

Thanks in advance...

回答1:

try

 If you need starting itself 

    // $('input[type=text]:eq(0)').prop('required', true);

 $("#selectBox").change(function () {
    var index=this.value-1;
    $('input[type=text]:gt(0)').prop('required', false);
   //  $('input[type=text]:eq(0)').prop('required', true);
    $('input[type=text]:eq('+index+')').prop('required', true);
 });

DEMO

来源：https://stackoverflow.com/questions/25286616/adding-validation-rules-depending-on-option-selected-from-dropdown-menu