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18 killer JavaScript single line code

1. Copy to clipboard
Easily copy any text to the clipboard using navigator.clipboard.writeText.
const copyToClipboard = (text) => navigator.clipboard.writeText(text); copyToClipboard("Hello World"); Copy code
2. Check whether the date is valid
Use the following code snippet to check if the given date is valid.
const isDateValid = (...val) => !Number.isNaN(new Date(...val).valueOf()); isDateValid("December 17, 1995 03:24:00"); // Result: true Copy code
3. Find out which day of the year
Find the day of a given date.
const dayOfYear = (date) => Math.floor((date - new Date(date.getFullYear(), 0, 0)) / 1000 / 60 / 60 / 24); dayOfYear(new Date()); // Result: 272 Copy code
4. Capitalize first string
Javascript has no built-in uppercase function, so we can use the following code.
const capitalize = str => str.charAt(0).toUpperCase() + str.slice(1)capitalize("follow for more")// Result: Follow for more Copy code
5. Find the number of days between two dates
Use the following code snippet to find the number of days between a given 2 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 Copy code
6. Clear all cookies
You can easily clear all cookies stored in the web page by using document.cookie to access the cookie and clear it.
const clearCookies = document.cookie.split(';').forEach(cookie => document.cookie = cookie.replace(/^ +/, '') .replace(/=.*/, `=;expires=${new Date(0).toUTCString()}; path=/`)); Copy code
7. Generate random hex
You can use the Math.random and padEnd properties to generate random hexadecimal colors.
const randomHex = () => `#${Math.floor(Math.random() * 0xffffff).toString(16).padEnd(6, "0")}` console.log(randomHex()); //Result: #92b008 Copy code
8. Remove duplicates from array
You can easily delete duplicates using Set in JavaScript.
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 ] Copy code
9. Get query parameters from URL
You can easily retrieve query parameters from the url by passing window.location or the original url goose. 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); }; getParameters(window.location) // Result: { search : "easy", page : 3 } Copy code
10. Record time from date
We can record time in the format of hour:: minute:: second from a given date.
const timeFromDate = date => date.toTimeString().slice(0, 8); console.log(timeFromDate(new Date(2021, 0, 10, 17, 30, 0))); // Result: "17:30:00" Copy code
11. Check whether the number is even or odd
const isEven = num => num % 2 === 0;console.log(isEven(2)); // Result: True Copy code
12. Average the numbers
Use the reduce method to find the average value between multiple numbers.
const average = (...args) => args.reduce((a, b) => a + b) / args.length; average(1, 2, 3, 4); // Result: 2.5 Copy code
13. Reverse string
You can easily reverse strings using split, reverse, and join methods.
const reverse = str => str.split('').reverse().join('');reverse('hello world'); // Result: 'dlrow olleh' Copy code
14. Check whether the array is empty
A simple single line program that checks whether the array is empty will return true or false.
const isNotEmpty = arr => Array.isArray(arr) && arr.length > 0; isNotEmpty([1, 2, 3]); // Result: true Copy code
15. Gets the selected text
Use the built-in getSelectionproperty to get the text selected by the user.
const getSelectedText = () => window.getSelection().toString(); getSelectedText(); Copy code
16. Scramble array
Using the sort and random methods, it's very easy to disrupt arrays.
const shuffleArray = (arr) => arr.sort(() => 0.5 - Math.random());console.log(shuffleArray([1, 2, 3, 4]));// Result: [ 1, 4, 3, 2 ] Copy code
17. Detect dark mode
Use the following code to check whether the user's device is in dark mode.
const isDarkMode = window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matchesconsole.log(isDarkMode) // Result: True or False Copy code
18. 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 Copy code
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