diff --git a/README.md b/README.md
index d5c4baeb6..33fc3bc12 100644
--- a/README.md
+++ b/README.md
@@ -53,29 +53,31 @@ This fork has the following changes:
 
 ### Removal of old JavaScript
 
-This fork uses jQuery.slim and downsized versions of Underscore.js, Jua.js, etc. etc., and has no support for Internet Explorer.
+This fork uses jQuery.slim, downsized/simplified versions of scripts and has no support for Internet Explorer.
+
+The result is faster and smaller download code (good for mobile networks).
 
 Things might work in Edge 15-18, Firefox 47-62 and Chrome 54-68 due to one polyfill for array.flat().
 
-|js/*       	|1.14.0   	|native   	| div     	|
-|-----------	|--------:	|--------:	|--------:	|
-|admin.js    	|2.130.942	|1.359.501	|	|
-|app.js      	|4.184.455	|3.127.807	|	|
-|boot.js     	|  671.522	|  117.510	|	|
-|libs.js     	|  647.614	|  508.324	|	|
-|polyfills.js	|  325.834	|        0	|	|
-|TOTAL js   	|7.960.367	|5.119.409	|	|
+|js/*       	|1.14.0   	|native   	|
+|-----------	|--------:	|--------:	|
+|admin.js    	|2.130.942	|1.359.501	|
+|app.js      	|4.184.455	|3.127.807	|
+|boot.js     	|  671.522	|  109.651	|
+|libs.js     	|  647.614	|  508.324	|
+|polyfills.js	|  325.834	|        0	|
+|TOTAL js   	|7.960.367	|5.105.283	|
 
-|js/min/*   	|1.14.0   	|native   	| div     	|
-|-----------	|--------:	|--------:	|--------:	|
-|admin.js    	|  252.147	|  177.094	|	|
-|app.js      	|  511.202	|  409.778	|	|
-|boot.js     	|   66.007	|   14.229	|	|
-|libs.js     	|  572.545	|  465.247	|	|
-|polyfills.js	|   32.452	|        0	|	|
-|TOTAL js/min	|1.434.353	|1.066.348	|368.005	|
+|js/min/*   	|1.14.0   	|native   	|
+|-----------	|--------:	|--------:	|
+|admin.js    	|  252.147	|  177.094	|
+|app.js      	|  511.202	|  409.778	|
+|boot.js     	|   66.007	|   13.380	|
+|libs.js     	|  572.545	|  465.247	|
+|polyfills.js	|   32.452	|        0	|
+|TOTAL js/min	|1.434.353	|1.065.499	|
 
-368.005 bytes is not much, but it feels faster.
+368.854 bytes is not much, but it feels faster.
 
 ### PHP73 branch
 
diff --git a/dev/Common/Booter.js b/dev/Common/Booter.js
index 53117c496..28d2492eb 100644
--- a/dev/Common/Booter.js
+++ b/dev/Common/Booter.js
@@ -13,92 +13,11 @@ window.__rlah_clear = () => clearHash();
 window.__rlah_data = () => RL_APP_DATA_STORAGE;
 
 /**
- * @param {string} styles
  * @returns {void}
  */
-function includeStyle(styles) {
-	const doc = window.document, style = doc.createElement('style');
-	style.type = 'text/css';
-	style.textContent = styles;
-//	style.appendChild(doc.createTextNode(styles));
-	doc.head.appendChild(style);
-}
-
-/**
- * @param {string} src
- * @returns {void}
- */
-function includeScr(src) {
-	const doc = window.document, script = doc.createElement('script');
-	script.type = 'text/javascript';
-	script.src = src;
-	doc.head.appendChild(script);
-}
-
-/**
- * @returns {boolean}
- */
-function includeLayout() {
-	const app = window.document.getElementById('rl-app');
-
-	require('Styles/@Boot.css');
-
-	if (app) {
-		const layout = require('Html/Layout.html');
-		app.innerHTML = ((layout && layout.default ? layout.default : layout) || '').replace(/[\r\n\t]+/g, '');
-		return true;
-	}
-
-	return false;
-}
-
-/**
- * @param {boolean} admin = false
- * @param {boolean} mobile = false
- * @param {boolean} mobileDevice = false
- * @returns {void}
- */
-function includeAppScr({ admin = false, mobile = false, mobileDevice = false }) {
-	let src = './?/';
-	src += admin ? 'Admin' : '';
-	src += 'AppData@';
-	src += mobile ? 'mobile' : 'no-mobile';
-	src += mobileDevice ? '-1' : '-0';
-	src += '/';
-
-	includeScr(
-		src +
-			(window.__rlah ? window.__rlah() || '0' : '0') +
-			'/' +
-			window.Math.random()
-				.toString()
-				.substr(2) +
-			'/'
-	);
-}
-
-/**
- * @returns {object}
- */
-function getRainloopBootData() {
-	let result = {};
-	const meta = window.document.getElementById('app-boot-data');
-
-	if (meta && meta.getAttribute) {
-		result = JSON.parse(meta.getAttribute('content')) || {};
-	}
-
-	return result;
-}
-
-/**
- * @param {string} additionalError
- * @returns {void}
- */
-function showError(additionalError) {
+function showError() {
 	const oR = window.document.getElementById('rl-loading'),
-		oL = window.document.getElementById('rl-loading-error'),
-		oLA = window.document.getElementById('rl-loading-error-additional');
+		oL = window.document.getElementById('rl-loading-error');
 
 	if (oR) {
 		oR.style.display = 'none';
@@ -108,60 +27,69 @@ function showError(additionalError) {
 		oL.style.display = 'block';
 	}
 
-	if (oLA && additionalError) {
-		oLA.style.display = 'block';
-		oLA.innerHTML = additionalError;
-	}
-
 	if (progressJs) {
 		progressJs.set(100).end();
 	}
 }
 
-/**
- * @param {string} description
- * @returns {void}
- */
-function showDescriptionAndLoading(description) {
-	const oE = window.document.getElementById('rl-loading'),
-		oElDesc = window.document.getElementById('rl-loading-desc');
-
-	if (oElDesc && description) {
-		oElDesc.innerHTML = description;
-	}
-
-	if (oE && oE.style) {
-		oE.style.opacity = 0;
-		window.setTimeout(() => {
-			oE.style.opacity = 1;
-		}, 300);
-	}
-}
-
 /**
  * @param {boolean} withError
- * @param {string} additionalError
  * @returns {void}
  */
-function runMainBoot(withError, additionalError) {
+function runMainBoot(withError) {
 	if (window.__APP_BOOT && !withError) {
 		window.__APP_BOOT(() => {
-			showError(additionalError);
+			showError();
 		});
 	} else {
-		showError(additionalError);
+		showError();
 	}
 }
 
 /**
+ * @param {mixed} data
  * @returns {void}
  */
-function runApp() {
-	const appData = window.__rlah_data();
+window.__initAppData = data => {
+	RL_APP_DATA_STORAGE = data;
+
+	window.__rlah_set();
+
+	const doc = window.document;
+
+	if (RL_APP_DATA_STORAGE) {
+		const css = RL_APP_DATA_STORAGE.IncludeCss,
+			theme = RL_APP_DATA_STORAGE.NewThemeLink,
+			description= RL_APP_DATA_STORAGE.LoadingDescriptionEsc || '',
+			oE = doc.getElementById('rl-loading'),
+			oElDesc = doc.getElementById('rl-loading-desc');
+
+		if (theme) {
+			(doc.getElementById('app-theme-link') || {}).href = theme;
+		}
+
+		if (css) {
+			const style = doc.createElement('style');
+			style.type = 'text/css';
+			style.textContent = css;
+//			style.appendChild(doc.createTextNode(styles));
+			doc.head.appendChild(style);
+		}
+
+		if (oElDesc && description) {
+			oElDesc.innerHTML = description;
+		}
+		if (oE && oE.style) {
+			oE.style.opacity = 0;
+			window.setTimeout(() => oE.style.opacity = 1, 300);
+		}
+	}
+
+	const appData = window.__rlah_data(), p = progressJs;
 
 	if (
 		jassl &&
-		progressJs &&
+		p &&
 		appData &&
 		appData.TemplatesLink &&
 		appData.LangLink &&
@@ -169,18 +97,16 @@ function runApp() {
 		appData.StaticAppJsLink &&
 		appData.StaticEditorJsLink
 	) {
-		const p = progressJs;
-
 		p.start().set(5);
 
 		const libs = () =>
 			jassl(appData.StaticLibJsLink).then(() => {
-				window.document.getElementById('rl-check').remove();
+				doc.getElementById('rl-check').remove();
 				if (appData.IncludeBackground) {
 					const img = appData.IncludeBackground.replace('{{USER}}', window.__rlah ? window.__rlah() || '0' : '0');
 					if (img) {
-						window.document.documentElement.classList.add('UserBackground');
-						window.document.body.style.backgroundImage = "url("+img+")";
+						doc.documentElement.classList.add('UserBackground');
+						doc.body.style.backgroundImage = "url("+img+")";
 					}
 				}
 			});
@@ -216,41 +142,40 @@ function runApp() {
 	} else {
 		runMainBoot(true);
 	}
-}
-
-/**
- * @param {mixed} data
- * @returns {void}
- */
-window.__initAppData = function(data) {
-	RL_APP_DATA_STORAGE = data;
-
-	window.__rlah_set();
-
-	if (RL_APP_DATA_STORAGE) {
-		if (RL_APP_DATA_STORAGE.NewThemeLink) {
-			(window.document.getElementById('app-theme-link') || {}).href = RL_APP_DATA_STORAGE.NewThemeLink;
-		}
-
-		if (RL_APP_DATA_STORAGE.IncludeCss) {
-			includeStyle(RL_APP_DATA_STORAGE.IncludeCss);
-		}
-
-		showDescriptionAndLoading(RL_APP_DATA_STORAGE.LoadingDescriptionEsc || '');
-	}
-
-	runApp();
 };
 
 /**
  * @returns {void}
  */
-window.__runBoot = function() {
+window.__runBoot = () => {
+	const doc = window.document,
+		app = doc.getElementById('rl-app');
+
 	if (!window.navigator || !window.navigator.cookieEnabled) {
-		window.document.location.replace('./?/NoCookie');
+		doc.location.replace('./?/NoCookie');
 	}
 
-	if (includeLayout()) {
-		includeAppScr(getRainloopBootData());
+	require('Styles/@Boot.css');
+
+	if (app) {
+		const layout = require('Html/Layout.html'),
+			meta = doc.getElementById('app-boot-data'),
+			options = meta ? JSON.parse(meta.getAttribute('content')) || {} : {},
+			script = doc.createElement('script');
+
+		app.innerHTML = ((layout && layout.default ? layout.default : layout) || '').replace(/[\r\n\t]+/g, '');
+
+		script.type = 'text/javascript';
+		script.src = './?/'
+			+ (options.admin ? 'Admin' : '')
+			+ 'AppData@'
+			+ (options.mobile ? 'mobile' : 'no-mobile')
+			+ (options.mobileDevice ? '-1' : '-0')
+			+ '/'
+			+ (window.__rlah ? window.__rlah() || '0' : '0')
+			+ '/'
+			+ window.Math.random().toString().substr(2)
+			+ '/';
+		doc.head.appendChild(script);
 	}
 };
diff --git a/dev/Html/Layout.html b/dev/Html/Layout.html
index b651c506c..40907cf08 100644
--- a/dev/Html/Layout.html
+++ b/dev/Html/Layout.html
@@ -8,7 +8,6 @@
 </div>
 <div id="rl-loading-error" class="thm-loading">
 	An error occurred. <br /> Please refresh the page and try again.
-	<div id="rl-loading-error-additional"></div>
 </div>
 <div id="rl-content">
 	<div id="rl-popups"></div>
diff --git a/dev/Styles/Layout.less b/dev/Styles/Layout.less
index 05349dd5a..c9e21226d 100644
--- a/dev/Styles/Layout.less
+++ b/dev/Styles/Layout.less
@@ -434,11 +434,6 @@ html.rl-ctrl-key-pressed {
 	display: none;
 }
 
-#rl-loading-error-additional {
-	margin-top: 20px;
-	font-size: 20px;
-}
-
 #rl-app{
 	display: none;
 }
diff --git a/vendors/Progress.js/minified/progress.min.js b/vendors/Progress.js/minified/progress.min.js
index 9e8f8bd45..b020437c0 100644
--- a/vendors/Progress.js/minified/progress.min.js
+++ b/vendors/Progress.js/minified/progress.min.js
@@ -1 +1 @@
-(e=>{function t(e){void 0!==e.length?this._targetElement=e:this._targetElement=[e],void 0===window._progressjsId&&(window._progressjsId=1),void 0===window._progressjsIntervals&&(window._progressjsIntervals={}),this._options={theme:"rainloop",overlayMode:!1,considerTransition:!0}}function r(){(function(){if(!document.querySelector(".progressjs-container")){var e=document.createElement("div");e.className="progressjs-container",document.body.appendChild(e)}}).call(this);var e=this;e._targetElement.forEach(t=>(function(e){if(e.hasAttribute("data-progressjs"))return;var t=function(e){var t={},r=0,s=0;"body"===e.tagName.toLowerCase()?(t.width=e.clientWidth,t.height=e.clientHeight):(t.width=e.offsetWidth,t.height=e.offsetHeight);for(;e&&!isNaN(e.offsetLeft)&&!isNaN(e.offsetTop);)r+=e.offsetLeft,s+=e.offsetTop,e=e.offsetParent;return t.top=s,t.left=r,t}.call(this,e);e.setAttribute("data-progressjs",window._progressjsId);var r=document.createElement("div");r.className="progressjs-progress progressjs-theme-"+this._options.theme,r.style.position="body"===e.tagName.toLowerCase()?"fixed":"absolute",r.setAttribute("data-progressjs",window._progressjsId);var o=document.createElement("div");o.className="progressjs-inner";var n=document.createElement("div");n.className="progressjs-percent",n.innerHTML="1%",o.appendChild(n),this._options.overlayMode&&"body"===e.tagName.toLowerCase()?(r.style.left=0,r.style.right=0,r.style.top=0,r.style.bottom=0):(r.style.left=t.left+"px",r.style.top=t.top+"px",r.style.width=t.width+"px",this._options.overlayMode&&(r.style.height=t.height+"px"));r.appendChild(o),document.querySelector(".progressjs-container").appendChild(r),s(e,1),++window._progressjsId}).call(e,t))}function s(e,t){t>=100&&(t=100),e.hasAttribute("data-progressjs")&&setTimeout(()=>{var r=o(e);r.style.width=parseInt(t)+"%",r=r.querySelector(".progressjs-percent");var s=parseInt(r.innerHTML.replace("%",""));((e,t,r)=>{var s=!0;t>r&&(s=!1);var o=10;!function e(t,r,n){var i=Math.abs(r-n);o=i<3?30:i<20?20:1,r-n!=0&&(t.innerHTML=(s?++r:--r)+"%",setTimeout(()=>e(t,r,n),o))}(e,t,r)})(r,s,parseInt(t))},50)}function o(e){var t=parseInt(e.getAttribute("data-progressjs"));return document.querySelector('.progressjs-container > .progressjs-progress[data-progressjs="'+t+'"] > .progressjs-inner')}var n=function(e){if("object"==typeof e)return new t(e);if("string"==typeof e){var r=document.querySelectorAll(e);if(r)return new t(r);throw new Error("There is no element with given selector.")}return new t(document.body)};n.version="0.1.0",n.fn=t.prototype={start:function(){return r.call(this),this},set:function(e){return function(e){var t=this;t._targetElement.forEach(r=>s.call(t,r,e))}.call(this,e),this},end:function(){return function(){void 0!==this._onBeforeEndCallback&&(!0===this._options.considerTransition?o(this._targetElement[0]).addEventListener("transitionend",this._onBeforeEndCallback,!1):this._onBeforeEndCallback.call(this));var e=parseInt(this._targetElement[0].getAttribute("data-progressjs")),t=this;if(t._targetElement.forEach(e=>{var r=o(e);if(r){var n=parseInt(r.style.width.replace("%","")),i=1;n<100&&(s.call(t,e,100),i=500),((e,t)=>{setTimeout(()=>{e.parentNode.className+=" progressjs-end",setTimeout(()=>{e.parentNode.parentNode.removeChild(e.parentNode),t.removeAttribute("data-progressjs")},1e3)},i)})(r,e)}}),window._progressjsIntervals[e])try{clearInterval(window._progressjsIntervals[e]),window._progressjsIntervals[e]=null,delete window._progressjsIntervals[e]}catch(e){}}.call(this),this},onbeforeend:function(e){if("function"!=typeof e)throw new Error("Provided callback for onbeforeend was not a function");return this._onBeforeEndCallback=e,this}},e.progressJs=n})(this);
+(e=>{const t=window,r=document,s=e=>void 0!==e;function o(e){this._targetElement=s(e.length)?e:[e],s(t._progressjsId)||(t._progressjsId=1),s(t._progressjsIntervals)||(t._progressjsIntervals={}),this._options={theme:"rainloop",overlayMode:!1,considerTransition:!0}}function n(e){if(!e.hasAttribute("data-progressjs")){var s=function(e){var t={},r=0,s=0;"body"===e.tagName.toLowerCase()?(t.width=e.clientWidth,t.height=e.clientHeight):(t.width=e.offsetWidth,t.height=e.offsetHeight);for(;e&&!isNaN(e.offsetLeft)&&!isNaN(e.offsetTop);)r+=e.offsetLeft,s+=e.offsetTop,e=e.offsetParent;return t.top=s,t.left=r,t}.call(this,e);e.setAttribute("data-progressjs",t._progressjsId);var o=r.createElement("div");o.className="progressjs-progress progressjs-theme-"+this._options.theme,o.style.position="body"===e.tagName.toLowerCase()?"fixed":"absolute",o.setAttribute("data-progressjs",t._progressjsId);var n=r.createElement("div");n.className="progressjs-inner";var i=r.createElement("div");i.className="progressjs-percent",i.innerHTML="1%",n.appendChild(i),this._options.overlayMode&&"body"===e.tagName.toLowerCase()?(o.style.left=0,o.style.right=0,o.style.top=0,o.style.bottom=0):(o.style.left=s.left+"px",o.style.top=s.top+"px",o.style.width=s.width+"px",this._options.overlayMode&&(o.style.height=s.height+"px")),o.appendChild(n),r.querySelector(".progressjs-container").appendChild(o),a(e,1),++t._progressjsId}}function a(e,t){t>=100&&(t=100),e.hasAttribute("data-progressjs")&&setTimeout(()=>{var r=i(e);r.style.width=parseInt(t)+"%",r=r.querySelector(".progressjs-percent");var s=parseInt(r.innerHTML.replace("%",""));((e,t,r)=>{var s=!0;t>r&&(s=!1);var o=10;!function e(t,r,n){var a=Math.abs(r-n);o=a<3?30:a<20?20:1,r-n!=0&&(t.innerHTML=(s?++r:--r)+"%",setTimeout(()=>e(t,r,n),o))}(e,t,r)})(r,s,parseInt(t))},50)}function i(e){var t=parseInt(e.getAttribute("data-progressjs"));return r.querySelector('.progressjs-container > .progressjs-progress[data-progressjs="'+t+'"] > .progressjs-inner')}var l=function(e){if("object"==typeof e)return new o(e);if("string"==typeof e){var t=r.querySelectorAll(e);if(t)return new o(t);throw new Error("There is no element with given selector.")}return new o(r.body)};l.version="0.1.0",l.fn=o.prototype={start:function(){if(!r.querySelector(".progressjs-container")){var e=r.createElement("div");e.className="progressjs-container",r.body.appendChild(e)}var t=this;return t._targetElement.forEach(e=>n.call(t,e)),t},set:function(e){var t=this;return t._targetElement.forEach(r=>a.call(t,r,e)),t},end:function(){var e=this;s(e._onBeforeEndCallback)&&(!0===e._options.considerTransition?i(e._targetElement[0]).addEventListener("transitionend",e._onBeforeEndCallback,!1):e._onBeforeEndCallback.call(e));var r=parseInt(e._targetElement[0].getAttribute("data-progressjs"));if(e._targetElement.forEach(t=>{var r=i(t);if(r){var s=parseInt(r.style.width.replace("%","")),o=1;s<100&&(a.call(e,t,100),o=500),((e,t)=>{setTimeout(()=>{e.parentNode.className+=" progressjs-end",setTimeout(()=>{e.parentNode.parentNode.removeChild(e.parentNode),t.removeAttribute("data-progressjs")},1e3)},o)})(r,t)}}),t._progressjsIntervals[r])try{clearInterval(t._progressjsIntervals[r]),t._progressjsIntervals[r]=null,delete t._progressjsIntervals[r]}catch(e){}return e},onbeforeend:function(e){return this._onBeforeEndCallback=e,this}},e.progressJs=l})(this);
diff --git a/vendors/Progress.js/src/progress.js b/vendors/Progress.js/src/progress.js
index a43f39161..ed67a2c8e 100644
--- a/vendors/Progress.js/src/progress.js
+++ b/vendors/Progress.js/src/progress.js
@@ -8,7 +8,10 @@
 
 (exports => {
   //Default config/variables
-  var VERSION = '0.1.0';
+  const VERSION = '0.1.0',
+    win = window,
+    doc = document,
+    defined = v => undefined !== v;
 
   /**
    * ProgressJs main class
@@ -17,17 +20,13 @@
    */
   function ProgressJs(obj) {
 
-    if (typeof obj.length != 'undefined') {
-      this._targetElement = obj;
-    } else {
-      this._targetElement = [obj];
-    }
+    this._targetElement = defined(obj.length) ? obj : [obj];
 
-    if (typeof window._progressjsId === 'undefined')
-      window._progressjsId = 1;
+    if (!defined(win._progressjsId))
+      win._progressjsId = 1;
 
-    if (typeof window._progressjsIntervals === 'undefined')
-      window._progressjsIntervals = {};
+    if (!defined(win._progressjsIntervals))
+      win._progressjsIntervals = {};
 
     this._options = {
       //progress bar theme
@@ -39,20 +38,6 @@
     };
   }
 
-  /**
-   * Start progress for specific element(s)
-   *
-   * @api private
-   * @method _createContainer
-   */
-  function _startProgress() {
-    //create the container for progress bar
-    _createContainer.call(this);
-
-    var p = this;
-    p._targetElement.forEach(item => _setProgress.call(p, item));
-  }
-
   /**
    * Set progress bar for specific element
    *
@@ -69,21 +54,21 @@
     //get target element position
     var targetElementOffset = _getOffset.call(this, targetElement);
 
-    targetElement.setAttribute("data-progressjs", window._progressjsId);
+    targetElement.setAttribute("data-progressjs", win._progressjsId);
 
-    var progressElementContainer = document.createElement('div');
+    var progressElementContainer = doc.createElement('div');
     progressElementContainer.className = 'progressjs-progress progressjs-theme-' + this._options.theme;
 
 
     //set the position percent elements, it depends on targetElement tag
     progressElementContainer.style.position = targetElement.tagName.toLowerCase() === 'body' ? 'fixed' : 'absolute';
 
-    progressElementContainer.setAttribute("data-progressjs", window._progressjsId);
-    var progressElement = document.createElement("div");
+    progressElementContainer.setAttribute("data-progressjs", win._progressjsId);
+    var progressElement = doc.createElement("div");
     progressElement.className = "progressjs-inner";
 
     //create an element for current percent of progress bar
-    var progressPercentElement = document.createElement('div');
+    var progressPercentElement = doc.createElement('div');
     progressPercentElement.className = "progressjs-percent";
     progressPercentElement.innerHTML = "1%";
 
@@ -110,25 +95,13 @@
     progressElementContainer.appendChild(progressElement);
 
     //append the element to container
-    var container = document.querySelector('.progressjs-container');
+    var container = doc.querySelector('.progressjs-container');
     container.appendChild(progressElementContainer);
 
     _setPercentFor(targetElement, 1);
 
     //and increase the progressId
-    ++window._progressjsId;
-  }
-
-  /**
-   * Set percent for all elements
-   *
-   * @api private
-   * @method _setPercent
-   * @param {Number} percent
-   */
-  function _setPercent(percent) {
-    var p = this;
-    p._targetElement.forEach(item => _setPercentFor.call(p, item, percent));
+    ++win._progressjsId;
   }
 
   /**
@@ -198,84 +171,7 @@
    */
   function _getPercentElement(targetElement) {
     var progressjsId = parseInt(targetElement.getAttribute('data-progressjs'));
-    return document.querySelector('.progressjs-container > .progressjs-progress[data-progressjs="' + progressjsId + '"] > .progressjs-inner');
-  }
-
-  /**
-   * Close and remove progress bar
-   *
-   * @api private
-   * @method _end
-   */
-  function _end() {
-
-    //call onBeforeEnd callback
-    if (typeof this._onBeforeEndCallback != 'undefined') {
-      if (this._options.considerTransition === true) {
-        //we can safety assume that all layers would be the same, so `this._targetElement[0]` is the same as `this._targetElement[1]`
-        _getPercentElement(this._targetElement[0]).addEventListener('transitionend', this._onBeforeEndCallback, false);
-      } else {
-        this._onBeforeEndCallback.call(this);
-      }
-    }
-
-    var progressjsId = parseInt(this._targetElement[0].getAttribute('data-progressjs'));
-
-    var p = this;
-    p._targetElement.forEach(currentElement => {
-      var percentElement = _getPercentElement(currentElement);
-
-      if (!percentElement)
-        return;
-
-      var existingPercent = parseInt(percentElement.style.width.replace('%', ''));
-
-      var timeoutSec = 1;
-      if (existingPercent < 100) {
-        _setPercentFor.call(p, currentElement, 100);
-        timeoutSec = 500;
-      }
-
-      //I believe I should handle this situation with eventListener and `transitionend` event but I'm not sure
-      //about compatibility with IEs. Should be fixed in further versions.
-      ((percentElement, currentElement) => {
-        setTimeout(() => {
-          percentElement.parentNode.className += " progressjs-end";
-
-          setTimeout(() => {
-            //remove the percent element from page
-            percentElement.parentNode.parentNode.removeChild(percentElement.parentNode);
-            //and remove the attribute
-            currentElement.removeAttribute("data-progressjs");
-          }, 1000);
-        }, timeoutSec);
-      })(percentElement, currentElement);
-	});
-
-    //clean the setInterval for autoIncrease function
-    if (window._progressjsIntervals[progressjsId]) {
-      //`delete` keyword has some problems in IE
-      try {
-        clearInterval(window._progressjsIntervals[progressjsId]);
-        window._progressjsIntervals[progressjsId] = null;
-        delete window._progressjsIntervals[progressjsId];
-      } catch(ex) { }
-    }
-  }
-
-  /**
-   * Create the progress bar container
-   *
-   * @api private
-   * @method _createContainer
-   */
-  function _createContainer() {
-    //first check if we have an container already, we don't need to create it again
-    if (!document.querySelector(".progressjs-container")) {
-      var containerElement = document.createElement("div");
-      containerElement.className = "progressjs-container";
-      document.body.appendChild(containerElement);
-    }
+    return doc.querySelector('.progressjs-container > .progressjs-progress[data-progressjs="' + progressjsId + '"] > .progressjs-inner');
   }
 
   /**
@@ -323,14 +219,14 @@
     }
     if (typeof (targetElm) === 'string') {
       //select the target element with query selector
-      var targetElement = document.querySelectorAll(targetElm);
+      var targetElement = doc.querySelectorAll(targetElm);
 
       if (targetElement) {
         return new ProgressJs(targetElement);
       }
       throw new Error('There is no element with given selector.');
     }
-    return new ProgressJs(document.body);
+    return new ProgressJs(doc.body);
   };
 
   /**
@@ -344,23 +240,80 @@
   //Prototype
   progressJs.fn = ProgressJs.prototype = {
     start: function() {
-      _startProgress.call(this);
-      return this;
+      //first check if we have an container already, we don't need to create it again
+      if (!doc.querySelector(".progressjs-container")) {
+        //create the container for progress bar
+        var containerElement = doc.createElement("div");
+        containerElement.className = "progressjs-container";
+        doc.body.appendChild(containerElement);
+      }
+      var p = this;
+      p._targetElement.forEach(item => _setProgress.call(p, item));
+      return p;
     },
     set: function(percent) {
-      _setPercent.call(this, percent);
-      return this;
+      var p = this;
+      p._targetElement.forEach(item => _setPercentFor.call(p, item, percent));
+      return p;
     },
     end: function() {
-      _end.call(this);
-      return this;
+      var p = this;
+      //call onBeforeEnd callback
+      if (defined(p._onBeforeEndCallback)) {
+        if (p._options.considerTransition === true) {
+          //we can safety assume that all layers would be the same, so `p._targetElement[0]` is the same as `p._targetElement[1]`
+          _getPercentElement(p._targetElement[0])
+            .addEventListener('transitionend', p._onBeforeEndCallback, false);
+        } else {
+          p._onBeforeEndCallback.call(p);
+        }
+      }
+
+      var progressjsId = parseInt(p._targetElement[0].getAttribute('data-progressjs'));
+
+      p._targetElement.forEach(currentElement => {
+        var percentElement = _getPercentElement(currentElement);
+
+        if (!percentElement)
+          return;
+
+        var existingPercent = parseInt(percentElement.style.width.replace('%', ''));
+
+        var timeoutSec = 1;
+        if (existingPercent < 100) {
+          _setPercentFor.call(p, currentElement, 100);
+          timeoutSec = 500;
+        }
+
+        //I believe I should handle this situation with eventListener and `transitionend` event but I'm not sure
+        //about compatibility with IEs. Should be fixed in further versions.
+        ((percentElement, currentElement) => {
+          setTimeout(() => {
+            percentElement.parentNode.className += " progressjs-end";
+
+            setTimeout(() => {
+              //remove the percent element from page
+              percentElement.parentNode.parentNode.removeChild(percentElement.parentNode);
+              //and remove the attribute
+              currentElement.removeAttribute("data-progressjs");
+            }, 1000);
+          }, timeoutSec);
+        })(percentElement, currentElement);
+      });
+
+      //clean the setInterval for autoIncrease function
+      if (win._progressjsIntervals[progressjsId]) {
+        //`delete` keyword has some problems in IE
+        try {
+          clearInterval(win._progressjsIntervals[progressjsId]);
+          win._progressjsIntervals[progressjsId] = null;
+          delete win._progressjsIntervals[progressjsId];
+        } catch(ex) { }
+      }
+      return p;
     },
     onbeforeend: function(providedCallback) {
-      if (typeof (providedCallback) === 'function') {
-        this._onBeforeEndCallback = providedCallback;
-      } else {
-        throw new Error('Provided callback for onbeforeend was not a function');
-      }
+      this._onBeforeEndCallback = providedCallback;
       return this;
     }
   };