$("#product1 :checkbox").click(function(){
    $(this)
        .closest('tr') // Find the parent row.
            .find(":input[type='text']") // Find text elements in that row.
                .attr('disabled',false).toggleClass('disabled') // Enable them.
                .end() // Go back to the row.
            .siblings() // Get its siblings
                .find(":input[type='text']") // Find text elements in those rows.
                .attr('disabled',true).removeClass('disabled'); // Disable them.
});

$(el).prop("disabled",!$(el).prop("disabled"))

$(el).prop('disabled', function() { return !$(this).prop('disabled') })

(function($) {
    $.fn.toggleDisabled = function() {
        return this.each(function() {
            var $this = $(this);
            if ($this.attr('disabled')) $this.removeAttr('disabled');
            else $this.attr('disabled', 'disabled');
        });
    };
})(jQuery);

(function($) {
    $.fn.toggleDisabled = function(){
        return this.each(function(){
            this.disabled = !this.disabled;
        });
    };
})(jQuery);

attr

$("#product1 :checkbox").click(function(){
  $(this)
   .closest('tr') // find the parent row
       .find(":input[type='text']") // find text elements in that row
           .attr('disabled',function(idx, oldAttr) {
               return !oldAttr; // invert disabled value
           })
           .toggleClass('disabled') // enable them
       .end() // go back to the row
       .siblings() // get its siblings
           .find(":input[type='text']") // find text elements in those rows
               .attr('disabled',function(idx, oldAttr) {
                   return !oldAttr; // invert disabled value
               })
               .removeClass('disabled'); // disable them
});