Gets the value of the browser Cookie

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

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

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

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 to clipboard

You can easily copy text to the clipboard using navigator.clipboard.writeText.

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

copyToClipboard("Hello World");

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

Find a day of the year

Find the given date.

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

dayOfYear(new Date());
// Result: 272

Uppercase string

Javascript does not have a built-in uppercase function, but we can use the following code to implement uppercase.

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

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

Find the number of days between two dates

Use the following code snippet to find the number of days between a 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

Clear all cookies

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

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

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

Remove duplicates from array

You can easily delete duplicates using Set in JavaScript. This is a straw.

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 ]

Get query parameters from URL

You can easily retrieve query parameters from the url by passing window.location or the original urlgoose. 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);
};

Output time from date

We can output the time in the format of hour::minutes::seconds 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"

Check whether the number is even or odd

const isEven = num => num % 2 === 0;

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

Average the 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

Scroll to top

You 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();

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'

Check whether the array is empty

A simple line of code can check whether the array is empty and return true or false.

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

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

Gets the selected text

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

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

getSelectedText();

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 ]

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)').matches

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

summary

I hope these 20 one-way code killer maces can help you. Please pay attention to me!!

Click on the bottom card / WeChat search to pay attention to the official account of "ID:gh_cc865e4c536b" (Tian Yuwen).