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const highlightText = (str, match) => {
  if (!str) return null;
  if (!match) return str;
  const regex = new RegExp(match, 'mig');
  return `>${str}<`.replace(/>[^<]+</gmi, (match) => match.replace(regex, '[$]')).slice(1, -1);
};

console.log(highlightText('lorem 0 erty o', 'o'));
console.log(highlightText('<p class="lorem">lorem ipsum dolor sit amet</p>', 'o'));
// l[$]rem 0 erty [$]

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ES6 JavaScript Compose Function

Definition

const compose = (...fns) =>
  fns.reduce((prevFn, nextFn) =>
    (...args) => prevFn(nextFn(...args)),
    (value) => value);

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const memoize = function(fn) {
  const cache = {};
  return function(...args) {
    const key = args.join();
    if (cache[key]) {
      console.log('from cache!');
      return cache[key];
    }
    return cache[key] = fn.apply(this, args);
  };

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const newArray = (size) => [...Array(size).keys()];
newArray(5); // [0, 1, 2, 3, 4]

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var factorial = function(num) {
  return !num ? 1 : num *= factorial(num - 1);
}

// Shorter ES6 variant
// const factorial = num => !num ? 1 : num *= factorial(num-1);

alert(factorial(6)); // 720
// https://jsfiddle.net/2ary59t0/157/

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const data = [1, [2, [3], 4], 5];

const sum = (data) => {
  return data.reduce((res, el) => {
    if (el.length) {
      return res + sum(el);
    }
    return res + el;
  }, 0);
}

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var a = [...Array(5000000).keys()];
var chunk = (data, center) => {
  const chunks = [];
  while (data.length)
    chunks.push(data.splice(0, center));
  return chunks;
}
var treeBuild = (array, tree = []) => {

  if (!array.length) return tree;

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function Queue() {

  var collection = [];
  
  this.dequeue = () => collection.shift();
  this.enqueue = (el) => collection.push(el);
  this.peek = () => collection[0];
  this.size = () => collection.length;
  this.get = () => collection.slice(0);
}

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const Stack = new function() {

  let data = [];

  this.pop = () => data.pop();
  this.push = (el) => data.push(el);
  this.peek = () => data[data.length - 1];
};

Stack.push(1);

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// Promise
const delay = (ms) => new Promise((resolve) => setTimeout(resolve, ms));

// or pseudo Promise
const delay = (time) => ({
  then: (cb) => setTimeout(cb, time)
});

// usage
delay(5000).then(…);