SilencerWeb

function doesElemExist(elemName) {
  return $(elemName).length > 0 ? true : false;
}

SilencerWeb

var gulp = require("gulp"),
    browserSync = require("browser-sync"),
    plugins = require("gulp-load-plugins")();
    plugins.del = require("del");

var path = {
  dest: {
    pug: 'dist',
    sass: 'dist/css',
    js: 'dist/js',

SilencerWeb

{
  "name": "gulpfile",
  "version": "1.0.0",
  "main": "index.js",
  "author": "Maksim Gorodov <Silencer.Web@mail.ru>",
  "license": "MIT",
  "dependencies": {
    "autoprefixer": "^7.1.1",
    "browser-sync": "^2.18.12",
    "css-mqpacker": "^6.0.1",

SilencerWeb

var _document = $(document);

_document.on("click", ".tabs__menu-link", function (e) {
  e.preventDefault();
  var _this = $(this),
      tabs = _this.closest(".tabs"),
      allTabsMenuItems = tabs.find(".tabs__menu-item"),
      allTabsContentItems = tabs.find(".tabs__content-item");

  allTabsMenuItems.removeClass("tabs__menu-item_active");

SilencerWeb

var _document = $(document),
    _window = $(window),
    body = $("body");

var modals = function () {
  var overlay = $(".overlay"),
      modalsWrapper = $(".modals-wrapper"),
      modal = $(".modal"),
      setTimeout;

SilencerWeb

var _document = $(document),
    mainNavList = $('.header__nav-list'),
    mainNavToggle = $('.header__nav-toggle'),
    header = $('.header');

_document.on('click', '.header__nav-toggle', function (e) {
  e.preventDefault();
  mainNavList.toggleClass('header__nav-list_active');
  mainNavToggle.toggleClass('header__nav-toggle_active');
  return false;

SilencerWeb

[Here is a site][1], in it a canvas (airplane), which lags when scrolling, appear artifacts, and in different ways, depending on what you scroll - with the mouse wheel or scrollbar. If you comment out parallax or video at the beginning, nothing changes. During the scrolling of calls to the house does not happen. Lags either from behind the airplane script, or because of a clearRect. How can I optimize and get rid of artifacts? The code on the [codepen][2].

P.S. Artifacts do not appear on the [codepen][2], they are only on the [site][1]!

JS-code:

      var scrolled;
      var positionsArr = [];
      var commonHeight = 0;
      var canvas = document.querySelector('#canvas');

SilencerWeb

var img = new Image();
var canvas = document.createElement('canvas');
var ctx = canvas.getContext('2d');
img.src = imageUrl;

img.onload = function () {
  canvas.width = img.width;
  canvas.height = 100;
  ctx.drawImage(img, 0, 0);
  img.style.display = 'none';

SilencerWeb

import React from 'react';

import Form from '../../components/Form';
import BooksList from '../../components/BooksList';

class App extends React.Component {
  state = {
    books: [
      {
        title: 'JavaScript and jQuery',

SilencerWeb

import React from 'react';
import styled from 'styled-components';

function Checkbox(props) {
  return (
    <div className={ props.className } onClick={ () => props.toggle(props.name) }>
      <input id={ props.name } type="checkbox" checked={ props.checked }/>
      { props.text }
      <span onClick={ props.uncheckAll }>Только</span>
    </div>