Question

I have two options that I am trying to filter between now, but will be adding in a third and maybe a fourth later on (for example: right now I am filtering between prices and reviews but will want to add more prices to the list and also another filter category like “rating” which would consist of 3, 4, or 5 stars).

Using the logic that I have listed below works fine, but I feel it will get really long and complicated (and unnecessary) as I go. I know there is a way to refactor the code I’m just wondering what the best way to go about it would be?
HTML:

  <select class="deals">
    <option value="deals-all">All deals</option>
    <option value="50">$50</option>
    <option value="25">$25</option>
  </select>

  <select class="reviews">
    <option value="reviews-all">All reviews</option>
    <option value="reviews-positive">Positive reviews</option>
    <option value="reviews-negative">Negative reviews</option>
  </select>

jQuery

 $('.reviews, .deals').change(function() {

var reviewsVal = $('.reviews :selected').val();
var dealsVal = $('.deals :selected').val();



 if((reviewsVal == 'reviews-all') && (dealsVal == 'deals-all')) {

      $('.review-positive').show();
 $('.review-negative').show();
 $('.deals-25').show();
 $('.deals-50').show();
 } 


else if((dealsVal == '50') && (reviewsVal == 'reviews-positive')) {
 $('.review-negative.deals-50').hide();
 $('.review-positive.deals-50').show();
 $('.review-negative.deals-25').hide();
 $('.review-positive.deals-25').hide();

 }

 else if((dealsVal == '50') && (reviewsVal == 'reviews-negative')) {
 $('.review-negative.deals-50').show();
 $('.review-positive.deals-50').hide();
 $('.review-negative.deals-25').hide();
 $('.review-positive.deals-25').hide();
 }

else if((dealsVal == '25') && (reviewsVal == 'reviews-positive')) {
 $('.review-negative.deals-50').hide();
 $('.review-positive.deals-50').hide();
 $('.review-negative.deals-25').hide();
 $('.review-positive.deals-25').show();
}

else if((dealsVal == '25') && (reviewsVal == 'reviews-negative')) {
 $('.review-negative.deals-50').hide();
 $('.review-positive.deals-50').hide();
 $('.review-negative.deals-25').show();
 $('.review-positive.deals-25').hide();
}

 else if((dealsVal == 'deals-all') && (reviewsVal == 'reviews-positive')) {
 $('.review-negative.deals-50').hide();
 $('.review-positive.deals-50').show();
 $('.review-negative.deals-25').hide();
 $('.review-positive.deals-25').show();
}

else if((dealsVal == 'deals-all') && (reviewsVal == 'reviews-negative')) {
 $('.review-negative.deals-50').show();
 $('.review-positive.deals-50').hide();
 $('.review-negative.deals-25').show();
 $('.review-positive.deals-25').hide();
}

else if((dealsVal == '50') && (reviewsVal == 'reviews-all')) {
 $('.review-negative.deals-50').show();
 $('.review-positive.deals-50').show();
 $('.review-negative.deals-25').hide();
 $('.review-positive.deals-25').hide();
}

else if((dealsVal == '25') && (reviewsVal == 'reviews-all')) {
 $('.review-negative.deals-50').hide();
 $('.review-positive.deals-50').hide();
 $('.review-negative.deals-25').show();
 $('.review-positive.deals-25').show();
}

else {
 $('.review-positive').show();
 $('.review-negative').show();
 $('.deals-25').show();
 $('.deals-50').show();
} 
});

$('.reviews-positive').click(function() {
$('.review-negative').hide();
$('.review-positive').show();
});

$('.reviews-negative').click(function() {
$('.review-positive').hide();
$('.review-negative').show();
});


});​

Hopefully you can see what I am going for, thanks for any input.

*EDIT: jsfiddle: http://jsfiddle.net/TXywp/1/

Answer 1

To get a dynamic result a standardized naming is the best way to go.
You start by standardizing the criteria selectors, giving them a general class and differentiating with id properties. Following a naming convetion for values is also recommended. This would produce something in the lines of

    <select id="deal" class="criteriaSelector">
      <option value="all">All deals</option>
      <option value="50">$50</option>
      <option value="25">$25</option>
    </select>

    <select id="review" class="criteriaSelector">
      <option value="all">All reviews</option>
      <option value="positive">Positive reviews</option>
      <option value="negative">Negative reviews</option>
    </select>

Then you give all the items you want to filter a generic class besides the filtering classes. I will use .item as an example. You will also want to be able to construct the class from selected value and criteria name so using the .{id}-{value} system will work perfectly. This will leave us with something in the lines of

    <div class="item review-positive deal-25"></div>
    <div class="item review-negative deal-50"></div>

This setup will allow us to build dynamic and extensible code:

    $('.criteriaSelector').change(function() {
      // Initialize criteria string
      var criteria = '';
      // Set value for all selector
      var showAll = true;

      // Iterate over all criteriaSelectors
      $('.criteriaSelector').each(function(){
        // Get value
        var val = $(this).children(':selected').val();
        // Check if this limits our results
        if(val !== 'all'){
          // Append selector to criteria
          criteria += '.' + $(this).attr('id') + '-' + val;
          // We don't want to show all results anymore
          showAll = false;
        }
      });
      // Check if results are limited somehow
      if(showAll){
        // No criterias were set so show all
        $('.item').show();
      } else {
        // Hide all items
        $('.item').hide();
        // Show the ones that were selected
        $(criteria).show();
      }

    });

Now adding a new criteria selector won’t require changes in this piece of code as long as naming conventions are followed.