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const wsConnection = new WebSocket('ws://localhost:3000/websocket');

wsConnection.onopen = () => {
  console.log('websocket connection is opened')
  wsConnection.send('A');
};

wsConnection.onmessage = event => {
  if (event.data === '9') {
    setTimeout(() => {

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// example below is using express and express-ws
app.ws('/websocket', (ws, req) => {
  ws.on('message', (msg) => {
    if (msg === 'A') {
      ws.send('9');
    }
  });
});

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// example below uses express.js
let counter = 0;
app.get('/longpolling', (req, res, next) => {
    const delay = Math.random();
    setTimeout(() => {
      res.send({
        random: delay,
        sequence: counter
      });
      counter++;

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import { fetchUrl } from 'fetch';

const registerLongPolling = () => {
    let counter = 0;
    fetchUrl('http://localhost:3000/longpolling', (error, meta, body) => {
        if (error) {
          return;
        }

        if (counter > 4) {

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/* On the server side, when get the request from eventSource,
 * response with content type as 'text/event-stream',
 * and write data in the format according to
 * https://www.w3.org/TR/2009/WD-eventsource-20090421/
 */
const constructSSEMsg = (res, id, data) => {
  res.write('id: ' + id + '\n');
  res.write('data: ' + data + '\n\n');
};

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const evtSource = new EventSource('/sse');
evtSource.onmessage = event => {
  try {
    const jsonData = JSON.parse(event.data);
    console.log(jsonData);
  } catch (e) {
    console.log(e);
  }
}

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const throttle = (func, delay) => {
  let executable = true;
  return () => {
    if (executable) {
      func();
      executable = false;
      setTimeout(() => {
        executable = true;
      }, delay);
    }

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function functionsProcessor(funcArr, initValue, ...args) {
  if(!funcArr.length) return initValue
  var cur = funcArr.shift()
  return functionsProcessor(funcArr, cur(initValue, ...args), ...args)
}

function functionsProcessor(funcArr, initValue, ...args) {
  for(var i = 0; i < funcArr.length; i++){
    initValue = funcArr[i](initValue, ...args)
  }

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var assert = require('assert')

function deepEqual(obj1, obj2){
  var keys1 = Object.keys(obj1)
  var keys2 = Object.keys(obj2)
  
  if(keys1.length !== keys2.length) return false
  
  for(var key in obj1){

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window.onload          dom tree, img, videos ready
document.onload        dom tree ready
$('document').ready()  dom tree ready