config.js file

 /**
 * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
 * For licensing, see LICENSE.md or http://ckeditor.com/license
 */

CKEDITOR.editorConfig = function( config ) {
	// Define changes to default configuration here.
	// For complete reference see:
	// http://docs.ckeditor.com/#!/api/CKEDITOR.config

	// config.filebrowserBrowseUrl = '././kcfinder/browse.php?type=files';
	// config.filebrowserImageBrowseUrl = '././kcfinder/browse.php?type=images';
	// config.filebrowserFlashBrowseUrl = '././kcfinder/browse.php?type=flash';
	// config.filebrowserUploadUrl = '/kcfinder/upload.php?type=files';
	// config.filebrowserImageUploadUrl = '/kcfinder/upload.php?type=images';
	// config.filebrowserFlashUploadUrl = '/kcfinder/upload.php?type=flash';
	// config.extraPlugins = 'wordcount';
	// config.entities = false;
	// config.enterMode = CKEDITOR.ENTER_BR;

	// The toolbar groups arrangement, optimized for two toolbar rows.
	config.toolbarGroups = [
		{ name: 'clipboard',   groups: [ 'clipboard', 'undo' ] },
		{ name: 'editing',     groups: [ 'find', 'selection', 'spellchecker' ] },
		// { name: 'links' },
		// { name: 'insert' },
		// { name: 'forms' },
		// { name: 'tools' },
		// { name: 'document',	   groups: [ 'mode', 'document', 'doctools' ] },
		// { name: 'others' },		
		{ name: 'basicstyles', groups: [ 'basicstyles', 'cleanup' ] },
		{ name: 'paragraph',   groups: [ 'list', 'indent', 'blocks', 'align' ] },
		'/',
		{ name: 'styles' },
		{ name: 'colors' },
		// { name: 'about' }
	];

	// Remove some buttons provided by the standard plugins, which are
	// not needed in the Standard(s) toolbar.
	config.removeButtons = 'Underline,Subscript,Superscript';

	// Set the most common block elements.
	config.format_tags = 'p;h1;h2;h3;pre';
	config.colorButton_enableAutomatic = true;
	// Simplify the dialog windows.
	config.removeDialogTabs = 'image:advanced;link:advanced';
};


CKEDITOR.on('instanceReady', function (e) {
    var instance = e.editor;
    instance.on("change", function (evt) {
        onCKEditorChange(evt.editor);
    });
    //key event handler is a hack, cause change event doesn't handle interaction with these keys 
    instance.on('key', function (evt) {
        var backSpaceKeyCode = 8;
        var deleteKeyCode = 46;
        if (evt.data.keyCode == backSpaceKeyCode || evt.data.keyCode == deleteKeyCode) {
            //timeout needed cause editor data will update after this event was fired
            setTimeout(function() {
                onCKEditorChange(evt.editor);
            }, 100);
        }
    });
    instance.on('mode', function () {
        if (this.mode == 'source') {
            var editable = instance.editable();
            editable.attachListener(editable, 'input', function (evt) {
                onCKEditorChange(instance);
            });
        }
    });
});

function onCKEditorChange(intance) {
    intance.updateElement();
    triggerElementChangeAndJqueryValidation($(intance.element.$));
}

function triggerElementChangeAndJqueryValidation(element) {
    element.trigger('keyup');
}

JQuery Validation Plugin with CK Editor

// Put this code in config.js file & then use jquery validation plugin with CkEditor

CKEDITOR.on('instanceReady', function (e) {
    var instance = e.editor;
    instance.on("change", function (evt) {
        onCKEditorChange(evt.editor);
    });
    //key event handler is a hack, cause change event doesn't handle interaction with these keys 
    instance.on('key', function (evt) {
        var backSpaceKeyCode = 8;
        var deleteKeyCode = 46;
        if (evt.data.keyCode == backSpaceKeyCode || evt.data.keyCode == deleteKeyCode) {
            //timeout needed cause editor data will update after this event was fired
            setTimeout(function() {
                onCKEditorChange(evt.editor);
            }, 100);
        }
    });
    instance.on('mode', function () {
        if (this.mode == 'source') {
            var editable = instance.editable();
            editable.attachListener(editable, 'input', function (evt) {
                onCKEditorChange(instance);
            });
        }
    });
});

function onCKEditorChange(intance) {
    intance.updateElement();
    triggerElementChangeAndJqueryValidation($(intance.element.$));
}

function triggerElementChangeAndJqueryValidation(element) {
    element.trigger('keyup');
}