jQuery('#sort-by').bind('change', function() {
Shopify.queryParams.sort_by = jQuery(this).val();
location.search = jQuery.param(Shopify.queryParams).replace(/\+/g, '%20');
});<div class="sort-collection-by">
<label for="sort-by">Sort by</label>
<select id="sort-by">
<option value="manual">Featured</option>
<option value="price-ascending">Price: Low to High</option>
<option value="price-descending">Price: High to Low</option>
<option value="title-ascending">A-Z</option>
<option value="title-descending">Z-A</option>
<option value="created-ascending">Oldest to Newest</option>
<option value="created-descending">Newest to Oldest</option>
<option value="best-selling">Best Selling</option>
</select>
</div>{% assign sorted_products = collection.products | sort: SELECT_CHOICE_HERE %}Bubble Sort, Selection sort, Merge sort