20 Killer JavaScript One Liners ☝️
Tags: javascript, github, programming, productivity
Published: 2021-09-19 08:47:44

## Hello Folks 👋

This is Savio here. I'm young dev with an intention to enhance as a successful web developer. I love building web apps with React. I have proved my superiority in frontend technologies.

Today, I'd like to share 20 Killer JavaScript one liners to make your life easier. Let's goooo 🚀

---

### Get Value of a brower Cookie

Retrieve the value of a cookie by accessing with `document.cookie`

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

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

### Convert RGB to Hex

```js
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

Easily copy any text to clipboard using `navigator.clipboard.writeText`.

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

copyToClipboard("Hello World");
```

### Check if Date is Valid

Use the following snippet to check if a given date is valid or not.

```js
const isDateValid = (...val) => !Number.isNaN(new Date(...val).valueOf());

isDateValid("December 17, 1995 03:24:00");
// Result: true
```

### Find the day of year

Find which is the day by a given date.

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

dayOfYear(new Date());
// Result: 272
```

### Capitalise a String

Javascript doesn't have an inbuilt capitalise function, so we can use the following code for the purpose.

```js
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 days

Find the days between 2 given days using the following snippet.

```js
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 a web page by accessing the cookie using `document.cookie` and clearing it.

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

### Generate Random Hex

You can generate random hex colors with `Math.random` and `padEnd` properties.

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

console.log(randomHex());
// Result: #92b008
```

### Remove Duplicated from Array

You can easily remove duplicates with `Set` in JavaScript. Its a life saver.

```js
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 Params from URL
You can easily retrieve query params from a url either by passing `window.location` or the raw URL `goole.com?search=easy&page=3`

```js
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 }
```

### Log Time from Date

We can log time, in the format `hour::minutes::seconds` from a given date.

```js
const timeFromDate = date => date.toTimeString().slice(0, 8);

console.log(timeFromDate(new Date(2021, 0, 10, 17, 30, 0))); 
// Result: "17:30:00"
```

### Check if a number is even or odd

```js
const isEven = num => num % 2 === 0;

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

### Find Average of Numbers

Find the average between multiple numbers using `reduce` method.

```js
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 `window.scrollTo(0, 0)` method to automatic scroll to top. Set both `x` and `y` as 0.

```js
const goToTop = () => window.scrollTo(0, 0);

goToTop();
```
### Reverse a string

You can easily reverse a string using `split`, `reverse` and `join` methods.

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

reverse('hello world');     
// Result: 'dlrow olleh'
```
### Check if array is empty

Simple one liner to check if an array is empty, will return `true` or `false`.

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

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

### Get Selected Text

Get the text the user has select using inbuilt `getSelection` property.

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

getSelectedText();
```

### Shuffle an Array 

Shuffling an array is super easy with `sort` and `random` methods. 

```js
const shuffleArray = (arr) => arr.sort(() => 0.5 - Math.random());

console.log(shuffleArray([1, 2, 3, 4]));
// Result: [ 1, 4, 3, 2 ]
```

### Detect Dark Mode

Check if a user's device is in dark mode with the following code.

```js
const isDarkMode = window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches

console.log(isDarkMode) // Result: True or False
```
---
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---
## 👀 Wrapping Up

Yeah, that's a wrap. Hope you enjoyed the article. Do not hesitate to share your feedback. I am on Twitter [@saviomartin7](https://twitter.com/SavioMartin7). Give a follow!

Follow me on Github [@saviomartin](https://github.com/saviomartin), Don't miss my amazing projects! 💯

Feedbacks are greatly appreciated! 🙌 Have an amazing day! 

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