Input and Textarea Validation in Twitter Bootstrap 3 (author: Anthony Vipond)

bootstrap3_validation.js

     /**
     * Construct feedback html for blur event on inputs and textareas
     * @param {String} icon_msg
     * @param {String} icon_class
     * @return {String} html
     */
    function get_feedback_html(icon_msg, icon_class) {
      var html = 
        '<span class="alert-msg"><i class="' + icon_class + '">' + icon_msg + '</i></span>';
      return html;
    }

    /**
     * Append or update a span based on validation result
     * @param {Object} element
     * @param {String} result
     * @param {String} icon_msg
     * @return {undefined} 
     */
    function append_or_update_span(element, result, icon_msg) {

      if ( element.next().is('span') ) {
          var icon_class = result == 'error' ? 'icon-remove-sign' : 'icon-ok-sign';
          element.parent()
            .removeClass('success error')
            .addClass(result);
          element.next().find('i')
            .removeClass()
            .addClass(icon_class)
            .text(icon_msg);
        } else {
          var form_feedback = get_feedback_html(icon_msg, icon_class);
          element.after(form_feedback);
        }
    }
       
    // Base form validation rules
    $('input, textarea').on('blur', function() {
      var self = $(this);
      // The following doesn't validate
      if ( $.trim($(this).val())  == '' ) {
        $(this).parent().addClass('error');
        var icon_msg = ' Please input a value';
        append_or_update_span(self, 'error', icon_msg);
      } else {
        // The following validates
        $(this).parent().addClass('success');
        var icon_msg = ' Value accepted';
        append_or_update_span(self, 'success', icon_msg);
      }
    }).on('focus', function() {
      $(this).removeClass('success error');
    });