SoFunction
Updated on 2025-04-07

Share 50 super useful JavaScript single-line code (recommended!)

Preface

In this post, I listed a series of 50 JavaScript single-line codes that are very useful when developing with vanilla js (≥ ES6). They are also an elegant way to solve problems using all the features that the language has provided us in the latest version.

I divided them into the following 5 categories:

  • date
  • String
  • number
  • Array
  • tool

Without further ado, I'll start right away, and I hope you find them helpful to you!

date

1. Is the date correct (valid)

This method is used to check if a given date is valid

const isDateValid = (...val) => !(new Date(...val).valueOf());
isDateValid("December 27, 2022 13:14:00");  // true

2. Know whether a date corresponds to the current date

It's as simple as converting two dates to the same format and comparing them.

is a Date instance.

const isCurrentDay = (date) =>  new Date().toISOString().slice(0, 10) === ().slice(0, 10);

3. How to know if a date is between two dates

We check if past dates are within the minimum-maximum range.

<min>, <max>, and <date> are Date instances.

const isBetweenTwoDates = ( min, max, date) => () >= () && () <= ();

4. Calculate the interval between two dates

This method is used to calculate the interval between two dates.

const dayDif = (date1, date2) => ((() - ()) / 86400000)
 
 
dayDif(new Date("2022-08-27"), new Date("2022-12-25"))  // 120

5. How to know if a date is on the weekend

The getDay method returns a number between 0 and 6, indicating that the given date is the day of the week.

is a Date instance.

const isWeekend = ( date ) => () === 6 || () === 0;

6. Check if the date is within one year

Similar to what we used to check if a date corresponds to the current date. In this case, we take the years and compare them.

and are two Date instances.

const isInAYear = (date, year) => () === new Date(`${year}`).getUTCFullYear();

7. Determine which day of the year the date is

This method is used to detect which day of the year the given date resides.

const dayOfYear = (date) => ((date - new Date((), 0, 0)) / 1000 / 60 / 60 / 24);
dayOfYear(new Date());   // 239

8. Convert hours to AM-PM format

We can use mathematical expressions to judge whether the elapsed time is less than or equal to 13 hours, so as to determine whether it is "morning" or "afternoon".

const toAMPMFormat= (h) => `${h % 12 === 0 ? 12 : h % 12}${h < 12 ? ' am.' : ' pm.'}`;

9. Format time

This method can be used to convert time to hh:mm:ss format.

const timeFromDate = date => ().slice(0, 8);
 
timeFromDate(new Date(2021, 11, 2, 12, 30, 0));  // 12:30:00
timeFromDate(new Date());  // now time 09:00:00

10. Convert hours to AM-PM format

We can use mathematical expressions to judge whether the elapsed time is less than or equal to 13 hours, so as to determine whether it is "morning" or "afternoon".

const toAMPMFormat= (h) => `${h % 12 === 0 ? 12 : h % 12}${h < 12 ? ' am.' : ' pm.'}`;

String

10.1 Initial capitalization of string

This method is used to capitalize the first letter of a string.

const capitalize = str => (0).toUpperCase() + (1)
capitalize("hello world")  // Hello world

10.2 Capitalization of the first letter of the sentence

We convert the first letter to capital letter and then use <join.> to attach the rest of the letters of the sentence

const capitalize = ([first, ...rest]) => `${()}${('')}`;

11. Convert a letter to his colleague's emoji

const letterToEmoji = c => (().charCodeAt() + 127365);

12. How to determine whether a string is a backdrop

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

13. Flip string

This method is used to flip a string and return the flipped string.

const reverse = str => ('').reverse().join('');
 
reverse('hello world');   // 'dlrow olleh'

14. Random strings

This method is used to generate random strings.

//Method Oneconst randomString = () =&gt; ().toString(36).slice(2);
randomString();
 
//Method 2const randomstr = ().toString(36).substring(7)

15. String truncation

This method truncates the string to a specified length.

const truncateString = (string, length) =>  < length ? string : `${(0, length - 3)}...`;
 
truncateString('Hi, I should be truncated because I am too loooong!', 36)   // 'Hi, I should be truncated because...'

16. Remove HTML from string

This method is used to remove HTML elements from a string.

const stripHtml = html => (new DOMParser().parseFromString(html,'text/html')). || '';

number

17. How to calculate the factorial of a number

const getFactorial = (n) => (n <= 1 ? 1 : n * getFactorial(n - 1));

18. How to get a Fibonacci sequence of a number

const getFibonacci = (n, memo = {}) => memo[n] || (n <= 2 ? 1 : (memo[n] = getFibonacci(n - 1, memo) + getFibonacci(n - 2, memo)));

19. How to find the factorial of a number

const getFactorial = (n) => (n <= 1 ? 1 : n * getFactorial(n - 1));

20. Determine whether a number is an odd or even number

This method is used to determine whether a number is an odd or even number.

const isEven = num => num % 2 === 0;
 
isEven(996);

21. Get the average of a set of numbers

const average = (.. .args) => ((a, b) => a + b) / ;
 
average(1, 2, 3, 4, 5); // 3

22. Determine a random integer from two integers

This method is used to get a random integer between two integers.

const random = (min, max) => (() * (max — min + 1) + min);
 
random(1, 50);

23. Round to the specified number of digits

This method can be used to round the number to the specified number.

const random = (min, max) => (() * (max — min + 1) + min);
 
random(1, 50);

Array

24. Copy an array to another array

const copyToArray = (arr) => [...arr];

25. Get unique elements from array

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

26. Random arrangement

The following code snippet disrupts the array in a very efficient way.

const shuffle = (arr) => (() => () - 0.5);

27. Group arrays by attributes

const groupBy = (arr, groupFn) =>   ( (grouped, obj) => ({...grouped, [groupFn(obj)]: [...(grouped[groupFn(obj)] || []), obj], }),{});

28. Check whether two arrays contain the same value

We can use the () and () methods to check whether the two arrays contain the same value.

const containSameValues= (arr1, arr2) =>   ().join(',') === ().join(',');

tool

29. Detect whether the object is empty

This method is used to detect whether a JavaScript object is empty.

const isEmpty = obj => (obj).length === 0 &&  === Object;

30. Switch variables

The following form can be used to exchange the values ​​of two variables without applying a third variable.

[foo, bar] = [bar, foo];

31. Random boolean value

This method returns a random boolean value. Using (), you can get a random number of 0-1 and compare it to 0.5, with half the probability of getting a true or false value.

const randomBoolean = () => () >= 0.5;
randomBoolean();

32. Get the type of variable

This method is used to get the type of a variable.

const trueTypeOf = (obj) => (obj).slice(8, -1).toLowerCase();
trueTypeOf(‘'); // string
trueTypeOf(0); // number
trueTypeOf(); // undefined
trueTypeOf(null); // null
trueTypeOf({}); // object
trueTypeOf([]); // array
trueTypeOf(0); // number
trueTypeOf(() => {}); // function

33. Color conversion

33.1 Convert HEX "#00000" to RGB(0,0,0)

const toRGB= (hex) =>
    hex.
        replace(/^#?([a-f\d])([a-f\d])([a-f\d])$/i, (_, r, g, b) => `#${r}${r}${g}${g}${b}${b}`)
        .substring(1)
        .match(/.{2}/g)
        .map((x) => parseInt(x, 16));

33.2 Convert RGB(0,0,0) to HEX"#00000"

const rgbToHex= (r,g,b) => "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);
rgbToHex(255, 255, 255);  // '#ffffff'

33.3 Randomly generate a hexadecimal color

This method is used to get random hexadecimal (HEX) color values.

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

34. Temperature and Fahrenheit conversion

34.1 Convert to Fahrenheit

const toFahrenheit= (celsius) => (celsius * 9) / 5 + 32;

34.2 Convert to Celsius

const toCelsius=  (fahrenheit) => (fahrenheit- 32) * 5 / 9;

35. Determine if the current tab is active

This method is used to check if the current tab is active.

const isTabInView = () => !;

36. Determine whether the current device is an Apple device

This method is used to check if the current device is an Apple device.

const isAppleDevice = () => /Mac|iPod|iPhone|iPad/.test();
isAppleDevice();

37. How to clear all cookies in your browser

const clearAllCookies = () => (';').forEach((c) => ( = (/^ +/, '').replace(/=.*/, `=;expires=${new Date().toUTCString()};path=/`)));

38. Check whether the function is an asynchronous function

const isAsyncFunction = (f) => (f) === '[object AsyncFunction]';

39. How to know if a piece of code is running in the browser

const runningInBrowser = typeof window === 'object' && typeof document === 'object';

40. How to know if a piece of code is running in node

const runningInNode= typeof process !== 'undefined' &&  != null &&  != null;

41. Detect dark mode

This is a very convenient way to check if the user has dark mode enabled on their browser.

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

42. Scroll the element to the top

One single-line method for scrolling elements is the use method.

//Method Oneconst toTop = (element) =&gt;
  ({ behavior: "smooth", block: "start" });

43. Scroll the element to the bottom

const toBottom = (element) =>
  ({ behavior: "smooth", block: "end" });

44.Navigate to the top of the page

This method is used to return to the top of the page.

const goToTop = () => (0, 0);
goToTop();

45. Whether to scroll to the bottom of the page

This method is used to determine whether the page is at the bottom.

const scrolledToBottom = () =>  +  >= ;

46. ​​Convert JSON to map

This function allows us to convert Map objects to JSON strings in a simple way.

const jsonToMap = (json) => new Map(((json)));

47. Generate a 128-bit UUID

This function allows us to generate a UUID with a 128-bit value to uniquely identify an object or entity.

const generateUUID = (a) =>   a     ? (a ^ ((() * 16) >> (a / 4))).toString(16)     : ([1e7] + -1e3 + -4e3 + -8e3 + -1e11).replace(         /[018]/g,         generateUUID);

48. Redirect to a URL

This method is used to redirect to a new URL.

const redirect = url =>  = url
redirect("/")

49. Open the browser print box

This method is used to open the browser's print box.

const showPrintDialog = () => ()

50. Delete all cookies

This method uses access cookies and clears all cookies stored on the web page.

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

Summarize

This is the end of this article about 50 super useful JavaScript single-line code. For more related JS single-line code content, please search for my previous articles or continue browsing the related articles below. I hope everyone will support me in the future!