jquery.form/validate plugin only allow submit if input is changed

问题

I'd like to use the jQuery.Form/Validate plugins to only allow my form to be submitted if any of inputs were actually changed.

There is callback logic for this using beforeSubmit: : http://jquery.malsup.com/form/#options-object. However, I can't seem to make it work.

Here's what I have so far:

$(document.body).on('click', 'input[type="submit"]', function(){
 var $form =$('form');

$form.validate({
  submitHandler: function($form) {
   $($form).ajaxSubmit({
  beforeSubmit: function(arr, $form){           
      var value = '', storedValue='';
      $($form+':input').each(function (index, el) {
  value=$(el).val();
  storedValue=$(el).data("stored");            
      if(value!=storedValue){
      console.log("Changed");   return true;
  } 
      else {
      return false; console.log("NOT changed");
  }
});   

...success handling, etc..

beforeSubmit: function(arr, $form) { 
  var value = '', storedValue='';
  $($form+':input').each(function (index, this) {
    value=this.value;
    storedValue=$(this).data("stored");            
        if(value!=storedValue){
          console.log("Changed");return true;
        } 
        else {
         return false; console.log("NOT changed");
        }
  });                   
}

Here's the HTML:

<form id="myForm">
  <input data-stored="my title" value="my title"/>
  <textarea data-stored="my description">my description</textarea>
  <input type="submit" value="submit/>
</form>

Currently the console.log shows, "Changed" regardless of whether the storedValue is equal or not to the input.

回答1:

First of all it will never show "Not Changed" since it returns false before it hits that part. You should filter out the submit button too since you probably aren't checking its value.

$($form+':input').not(':submit').each(function(index, this) {
    value = this.value;
    storedValue = $(this).data("stored");
    if (value != storedValue) {
        console.log("Changed");
        return true;      
    }
    else {       
        console.log("NOT changed");
        return false;
    }
});

UPDATE With great assistance from @wirey, together we've (@timrpeterson and @wirey) put together a solution. Instead of returning true/false within the each() loop, I incremented a value ,totalChanged, and assessed after the each() loop whether or not it was greater than 0.

here's the code:

beforeSubmit: function(arr, $form){   
var value = '', storedValue='', totalChanged=0;
$('#myForm :input').not(':submit,:hidden').each(function (i, el) {
  //console.log($(this));
    console.log($($form));
    value=$(el).val(); 
    storedValue=$(el).data("stored");          
    if (value != storedValue) {  
      totalChanged++;    
    }
    else {     
    }
}); //each

  if(totalChanged>0){
     console.log("at least one changed");
     return true;
  }
  else{
     console.log("All NOT changed");
     return false;
  }
} //beforeSubmit

来源：https://stackoverflow.com/questions/10984196/jquery-form-validate-plugin-only-allow-submit-if-input-is-changed