Commonly Used JavaScript Utility Functions

const copyToClipboard = (text) => navigator.clipboard.writeText(text);
 
// example usage
copyToClipboard('Hello, World!');

const getDayOfYear = (date) => {
  // Both dates at UTC midnight, so a daylight saving change in between
  // cannot leave a day an hour short
  const day = Date.UTC(date.getFullYear(), date.getMonth(), date.getDate());
  // Day zero is December 31 of the year before
  const dayZero = Date.UTC(date.getFullYear(), 0, 0);
 
  return (day - dayZero) / (24 * 60 * 60 * 1000);
};
 
// example usage
getDayOfYear(new Date(2024, 8, 20)); // 264 (months start at 0: 8 is September)

const removeDuplicates = (arr) =>
  arr.filter((item, index) => arr.indexOf(item) === index);
 
// example usage
removeDuplicates([1, 2, 2, 3, 4, 4, 5]); // [1, 2, 3, 4, 5]

const selectRandomItem = (arr) => arr[Math.floor(Math.random() * arr.length)];
 
// example usage
selectRandomItem([1, 2, 3, 4, 5]); // A random number between 1 and 5

const grayScale = (r, g, b) => 0.2126 * r + 0.7152 * g + 0.0722 * b;
 
// example usage
grayScale(255, 255, 255);

const parseQuery = (url) => Object.fromEntries(new URL(url).searchParams);
 
// example usage
parseQuery('https://example.com?foo=bar&baz=qux');
// {foo: 'bar', baz: 'qux'}

const pick = (obj, ...keys) =>
  Object.fromEntries(Object.entries(obj).filter(([key]) => keys.includes(key)));
 
// example usage
pick({ a: 1, b: 2, c: 3 }, 'a', 'c'); // {a: 1, c: 3}

const getRandomHexColor = () => {
  const color = Math.floor(Math.random() * 0x1000000); // 0x000000 to 0xffffff
  return '#' + color.toString(16).padStart(6, '0');
};
 
// example usage
getRandomHexColor();

const removeTag = (fragment) =>
  new DOMParser().parseFromString(fragment, 'text/html').body.textContent || '';
 
// example usage
removeTag('<p>Hello, World!</p>'); // 'Hello, World!'