DEV Community

Cover image for Our favorite javascript one-liners
Everly Health profile image J.
J. for Everly Health

Posted on • Edited on

Our favorite javascript one-liners

#javascript #snippet #webdev #programming

These are our favorite one-liners that we've used and forgot existed because they work so well 😁.

Generate a random hex color 

const color = () => '#' + Math.floor(Math.random() * (0xffffff + 1)).toString(16).padEnd(6, '0');
Enter fullscreen mode Exit fullscreen mode

Remove array duplicates 

const removeDuplicates = arr => [...new Set(arr)];
Enter fullscreen mode Exit fullscreen mode

Reverse a string 

const reverseString = str => [...str].reverse().join()
Enter fullscreen mode Exit fullscreen mode

Clear all cookies

Note: This will not always work because cookies can be set to not be changed from the front-end. (Thanks @lukeshiru!)

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

Remove falsy values from an array 

const removeFalsyValues = arr => arr.filter(x=>x)

/** OR **/

const removeFalsyValues = arr => arr.filter(Boolean)
Enter fullscreen mode Exit fullscreen mode

Get the value of a query parameter from a url

Pass in the url and the parameter that you're looking for the value of, and this function will return the value to you

const getQueryParam = (url, param) => new URL(url).searchParams.get(queryParam);
Enter fullscreen mode Exit fullscreen mode

Copy to clipboard 

const copyToClipboard = (text) => navigator.clipboard.writeText(text);
Enter fullscreen mode Exit fullscreen mode

Get selected text 

const getSelectedText = () => window.getSelection().toString();
Enter fullscreen mode Exit fullscreen mode

Scroll to Top 

const scrollToTop = () => window.scrollTo(0, 0);
Enter fullscreen mode Exit fullscreen mode

Scroll to Bottom 

const scrollToBottom = () => window.scrollTo(0, document.body.scrollHeight);
Enter fullscreen mode Exit fullscreen mode

Toggle a Boolean 

const toggleBool = bool => !bool;
Enter fullscreen mode Exit fullscreen mode

Convert Fahrenheit / Celsius 

const cToF = (celsius) => celsius * 9/5 + 32;
const fToC = (fahrenheit) => (fahrenheit - 32) * 5/9;
Enter fullscreen mode Exit fullscreen mode

Check if a property exists on an object

I know this seems like more than a one-liner, but given an object already exists, checking for properties on that object is definitely a one-liner 😁

const myObject = {
  id: 1,
  name: 'Tron',
  group: 'decepticons'
};

const isGroupExists = 'group' in myObject;
console.log(isGroupExists); // true

const isMusicExists = 'music' in myObject;
console.log(isMusicExists); // false
Enter fullscreen mode Exit fullscreen mode

Thanks

Special thanks to Fernando, José, @patricia_br, @lukeshiru, @lionelrowe and @jonrandy for adding to this list and optimizing!

Top comments (12)

Collapse
 
lionelrowe profile image
lionel-rowe •

Math.floor(Math.random() * 0xffffff) gives numbers in the range 0..0xfffffe, not 0..0xffffff. You want Math.floor(Math.random() * (0xffffff + 1)), i.e. Math.floor(Math.random() * 0x1000000) 😉

Collapse
 
stackcache profile image
J. •

this guy hexes...

Collapse
 
jonrandy profile image
Jon Randy 🎖️ • • Edited

Reverse string can be shortened to:

const reverseString = str => [...str].reverse().join()
Enter fullscreen mode Exit fullscreen mode

Your version also has an issue with unicode, which the above function fixes:

"🤓🚀🐍".split('').reverse().join('')   //  "\udc0d🚀🔓\ud83e"

[..."🤓🚀🐍"].reverse().join('')   // "🐍🚀🤓"
Enter fullscreen mode Exit fullscreen mode

Filtering falsy values can also be shortened:

const removeFalsyValues = arr => arr.filter(x=>x)
Enter fullscreen mode Exit fullscreen mode
Collapse
 
stackcache profile image
J. •

niiiiiice

Collapse
 
hrushalnikhare profile image
Hrushal •

Cool really helped me!

Collapse
 
stackcache profile image
J. •

sweet! thanks for the feedback!

Collapse
 
posandu profile image
Posandu •

Cheers!

Collapse
 
stackcache profile image
J. •

🔥

Collapse
 
flyingcrp profile image
flyingCrp •

JavaScript's magic

Collapse
 
sergio_inge profile image
Sergio Martín •

Filtering falsy values can also be done like...

const removeFalsyValues = arr => arr.filter(Boolean)

Thanks for your good article!

Collapse
 
stackcache profile image
J. •

we actually had it this way originally 😄. both ways work, i think the updated one may save a character or two. i'll add a note, so that both are covered though!

Collapse
 
oricohen profile image
OriCohen05 •

Really cool
Thanks!

View full discussion (12 comments)

Some comments have been hidden by the post's author - find out more

Read next

harold_defree profile image

Month 1: The Kickoff – Building the Foundation

Harold Defree -

cp_nandani profile image

Building a Better Monorepo with TypeScript, Turborepo, or Nx

Nandani Sharma -

witcher_1001 profile image

🌐 SSH Tunneling: Securely Connect to Remote Networks Like a Pro

The Witcher -

terieyenike profile image

Building a Console-Based Calculator in C#

teri -