Commonly Used JavaScript Utility Functions

1. Copy Text to Clipboard

javascript

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

2. Get nth Day of the Year

javascript

const getDayOfYear = (date) =>
  Math.floor((date - new Date(date.getFullYear(), 0, 0)) / 1000 / 60 / 60 / 24);
 
// example usage
getDayOfYear(new Date(2024, 9, 20)); // 274

3. Remove Duplicates from an Array

javascript

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]

4. Select a Random Item from an Array

javascript

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

5. Grayscale a RGB Color Value (Based on the luminance of the color)

javascript

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

6. Parse Query Parameters from a URL

javascript

const parseQuery = (url) => {
  q = {};
 
  url.replace(/([^?&=]+)=([^&]*)/g, (_, key, value) => (
    q[key] = value;
  ));
 
  return q;
}
 
// example usage
parseQuery('https://example.com?foo=bar&baz=qux');
// {foo: 'bar', baz: 'qux'}

7. Pick Keys from an Object

javascript

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}

8. Get a Random Hex Color

javascript

const getRandomHexColor = () =>
  '#' + Math.floor(Math.random() * * 0xffffff).toString(16).padEnd(6, '0');
 
// example usage
getRandomHexColor();

9. Remove Tag from HTML

javascript

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

Thank you for reading! I hope you found this helpful!

Happy coding!