Share 20 JavaScript one-line codes

1. Get the value of browser cookie
2. Convert RGB to Hexadecimal
3. Copy to clipboard
4. Check if the date is valid
5. Find the day of the year
6. Uppercase strings
7. Find the number of days between two dates
8. Clear all cookies
9. Generate random hexadecimal
10. Remove duplicates from an array
11. Get query parameters from URL
12. Output time from date
13. Check if a number is even or odd
14. Find the average of numbers
15. Scroll to Top
16. Reverse a string
17. Check if the array is empty
18. Get the selected text
19. Shuffle an array
20. Detect Dark Mode

1. Get the value of browser cookie

Retrieve the value of cookie by using document.cookie accessor.

const cookie = name => `; ${document.cookie}`.split(`; ${name}=`).pop().split(';').shift();

cookie('_ga');
// Result: "GA1.2.1929736587.1601974046"

2. Convert RGB to Hexadecimal

const rgbToHex = (r, g, b) =>
  "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);

rgbToHex(0, 51, 255); 
// Result: #0033ff

3. Copy to clipboard

Text can be easily copied to the clipboard using navigator.clipboard.writeText .

const copyToClipboard = (text) => navigator.clipboard.writeText(text);

copyToClipboard("Hello World");

4. Check if the date is valid

Use the following code snippet to check whether a given date is valid or not.

const isDateValid = (...val) => !Number.isNaN(new Date(...val).valueOf());

isDateValid("December 17, 1995 03:24:00");
// Result: true

5. Find the day of the year

Find a given date.

const dayOfYear = (date) =>
  Math.floor((date - new Date(date.getFullYear(), 0, 0)) / 1000 / 60 / 60 / 24);

dayOfYear(new Date());
// Result: 272

6. Uppercase strings

Javascript does not have a built-in uppercase function, but we can achieve uppercase using the following code.

const capitalize = str => str.charAt(0).toUpperCase() + str.slice(1)

capitalize("follow for more")
// Result: Follow for more

7. Find the number of days between two dates

Use the following code snippet to find the number of days between the given two dates.

const dayDif = (date1, date2) => Math.ceil(Math.abs(date1.getTime() - date2.getTime()) / 86400000)

dayDif(new Date("2020-10-21"), new Date("2021-10-22"))
// Result: 366

8. Clear all cookies

You can easily clear all cookie stored in a web page by accessing cookie using document.cookie and clearing it.

const clearCookies = document.cookie.split(';').forEach(cookie => document.cookie = cookie.replace(/^ +/, '').replace(/=.*/, `=;expires=${new Date(0).toUTCString()};path=/`));

9. Generate random hexadecimal

You can generate random hexadecimal colors using Math.random and padEnd property.

const randomHex = () => `#${Math.floor(Math.random() * 0xffffff).toString(16).padEnd(6, "0")}`;

console.log(randomHex());
// Result: #92b008

10. Remove duplicates from an array

You can easily remove duplicates using Set in JavaScript . This is a life saver.

const removeDuplicates = (arr) => [...new Set(arr)];

console.log(removeDuplicates([1, 2, 3, 3, 4, 4, 5, 5, 6]));
// Result: [ 1, 2, 3, 4, 5, 6 ]

11. Get query parameters from URL

You can retrieve query parameters from url easy by passing window.location or the original URLgoole.com?search=easy&page=3 .

const getParameters = (URL) => {
  URL = JSON.parse('{"' + decodeURI(URL.split("?")[1]).replace(/"/g, '\\"').replace(/&/g, '","').replace(/=/g, '":"') + '"}');
  return JSON.stringify(URL);
};

12. Output time from date

We can output the time from a given date in the format of hour::minutes::seconds .

const timeFromDate = date => date.toTimeString().slice(0, 8);

console.log(timeFromDate(new Date(2021, 0, 10, 17, 30, 0))); 
// Result: "17:30:00"

13. Check if a number is even or odd

const isEven = num => num % 2 === 0;

console.log(isEven(2)); 
// Result: True

14. Find the average of numbers

Use the reduce method to find the average of multiple numbers.

const average = (...args) => args.reduce((a, b) => a + b) / args.length;

average(1, 2, 3, 4);
// Result: 2.5

15. Scroll to Top

We can use the window.scrollTo(0, 0) method to automatically scroll to the top. Set both x and y to 0.

const goToTop = () => window.scrollTo(0, 0);

goToTop();

16. Reverse a string

You can easily reverse a string using split , reverse , and join methods.

const reverse = str => str.split('').reverse().join('');

reverse('hello world');     
// Result: 'dlrow olleh'

17. Check if the array is empty

With just one line of code you can check if an array is empty and return true or false .

const isNotEmpty = arr => Array.isArray(arr) && arr.length > 0;

isNotEmpty([1, 2, 3]);
// Result: true

18. Get the selected text

Use the built-in getSelection property to get the text selected by the user.

const getSelectedText = () => window.getSelection().toString();

getSelectedText();

19. Shuffle an array

It is very easy to shuffle an array using sort and random methods.

const shuffleArray = (arr) => arr.sort(() => 0.5 - Math.random());

console.log(shuffleArray([1, 2, 3, 4]));
// Result: [ 1, 4, 3, 2 ]

20. Detect Dark Mode

Use the following code to check if the user's device is in dark mode.

const isDarkMode = window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches

console.log(isDarkMode) // Result: True or False

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