title: jquery validation plugin, how can i validate a field but not have it required
body: <p>I am using jquery validation plugin for clientside validation of a form. </p>
  
  <p>I have a field StandardPrice which is required and needs to be a number. The validation code below works perfect.</p>
  
  <p>I have another field in a form called MinPrice that is optional but I do want to validate that if a user puts something in there that it is a number.  I thought by removing the <strong>required: true</strong> but still having the <strong>number: true</strong> it would support this but it seems like its not allowing me to leave this field blank (even though I don't have <strong>required: true</strong> set)</p>
  
  <p>Does jquery validation plugin support validating a field IF its populated but leaving it alone if its blank.</p>
  
  <p>Here is my code:</p>
  
  <pre><code> $("#productForm").validate({
       rules: {
           StandardPrice: {
               required: true,
               number: true
           },
           MinPrice: {
               number: true
           }
       }
   });
  </code></pre>
  
  <p>Here is a screenshot of the validation when the field is empty:</p>
  
  <p><img src="https://i.stack.imgur.com/n443O.png" alt="enter image description here"></p>
  
  <p>and here is my html output (my actual code is using a lot of HTML.helpers() and Html.ValidationMessageFor()</p>
  
  <pre><code> &lt;form action="/Product/EditProduct" id="productForm" method="post"&gt;    &lt;fieldset&gt;
      &lt;legend&gt;Product&lt;/legend&gt;
  
      &lt;div class="editor-label"&gt;
          &lt;label for="Product_Name"&gt;Name&lt;/label&gt;
      &lt;/div&gt;
  
      &lt;div class="editor-field"&gt;
          &lt;input class="required" id="Product_Name" name="Product.Name" style="width:450px;" type="text" value="Linzer Tart" /&gt;
          &lt;span class="field-validation-valid" data-valmsg-for="Product.Name" data-valmsg-replace="true"&gt;&lt;/span&gt;
      &lt;/div&gt;
  
      &lt;div class="editor-label"&gt;
  
          &lt;label for="Product_StandardPrice"&gt;StandardPrice&lt;/label&gt;
      &lt;/div&gt;
      &lt;div class="editor-field"&gt;
          &lt;input data-val="true" data-val-number="The field StandardPrice must be a number." data-val-required="The StandardPrice field is required." id="Product_StandardPrice" name="Product.StandardPrice" style="width:45px;text-align:right;" type="text" value="1.50" /&gt;
          &lt;span class="field-validation-valid" data-valmsg-for="Product.StandardPrice" data-valmsg-replace="true"&gt;&lt;/span&gt;
      &lt;/div&gt;
  
      &lt;div class="editor-label"&gt;
          &lt;label for="Product_MiniPrice"&gt;MiniPrice&lt;/label&gt;
  
      &lt;/div&gt;
      &lt;div class="editor-field"&gt;
          &lt;input data-val="true" data-val-number="The field MiniPrice must be a number." data-val-required="The MiniPrice field is required." id="Product_MiniPrice" name="Product.MiniPrice" style="width:45px;text-align:right;" type="text" value="0.00" /&gt;
          &lt;span class="field-validation-valid" data-valmsg-for="Product.MiniPrice" data-valmsg-replace="true"&gt;&lt;/span&gt;
      &lt;/div&gt;
  
      &lt;input data-val="true" data-val-number="The field Id must be a number." data-val-required="The Id field is required." id="Product_Id" name="Product.Id" type="hidden" value="102" /&gt;
  
      &lt;p&gt;
          &lt;input type="submit" value="Save" /&gt;
  
      &lt;/p&gt;
  &lt;/fieldset&gt;
  </code></pre>
  
  <p></p>