Our favorite javascript one-liners

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');

Remove array duplicates

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

Reverse a string

const reverseString = str => [...str].reverse().join()

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=/'));

Remove falsy values from an array

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

/** OR **/

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

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);

Copy to clipboard

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

Get selected text

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

Scroll to Top

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

Scroll to Bottom

const scrollToBottom = () => window.scrollTo(0, document.body.scrollHeight);

Toggle a Boolean

const toggleBool = bool => !bool;

Convert Fahrenheit / Celsius

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

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

Thanks

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

Comments

[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) 😉

[J.]

this guy hexes...

[Jon Randy 🎖️]

Reverse string can be shortened to:

const reverseString = str => [...str].reverse().join()

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

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

[..."🤓🚀🐍"].reverse().join('')   // "🐍🚀🤓"

Filtering falsy values can also be shortened:

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

[J.]

niiiiiice

[Hrushal]

Cool really helped me!

[J.]

sweet! thanks for the feedback!

[Posandu]

Cheers!

[J.]

🔥

[flyingCrp]

JavaScript's magic

[Sergio Martín]

Filtering falsy values can also be done like...

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

Thanks for your good article!

[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!

[OriCohen05]

Really cool
Thanks!