Javascript snippets you need to know right now 🔥 - #3
Tags: javascript, webdev, beginners, programming
Published: 2021-11-24 12:45:58

Hello friends!
Hope you all are doing great. 
Welcome back to my series of posts where I give 10 JS snippets every week amounting over to 50 essential JS snippets.

Here's the previous edition if you missed it.
{% link https://dev.to/abhirajb/javascript-snippets-you-need-to-know-right-now-2-2pom %}

1️⃣ average
This snippet returns the average of two or more numerical values.
```js
const average = (...nums) => nums.reduce((acc, val) => acc + val, 0) / nums.length;
average(...[1, 2, 3]); // 2
average(1, 2, 3); // 2
```

2️⃣ averageBy
This snippet returns the average of an array after initially doing the mapping of each element to a value using a given function.
```js
const averageBy = (arr, fn) =>
  arr.map(typeof fn === 'function' ? fn : val => val[fn]).reduce((acc, val) => acc + val, 0) /
  arr.length;
  
averageBy([{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }], o => o.n); // 5
averageBy([{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }], 'n'); // 5
```

3️⃣ capitalizeEveryWord
This snippet capitalizes the first letter of every word in a given string.
```js
const capitalizeEveryWord = str => str.replace(/\b[a-z]/g, char => char.toUpperCase());

capitalizeEveryWord('hello world!'); // 'Hello World!'
```

4️⃣ Create Directory
This snippet uses existsSync() to check whether a directory exists and then mkdirSync() to create it if it doesn’t.
```js
const fs = require('fs');
const createDirIfNotExists = dir => (!fs.existsSync(dir) ? fs.mkdirSync(dir) : undefined);
createDirIfNotExists('test'); 
// creates the directory 'test', if it doesn't exist
```

5️⃣ deepFlatten
This snippet flattens an array recursively.
```js
const deepFlatten = arr => [].concat(...arr.map(v => (Array.isArray(v) ? deepFlatten(v) : v)));

deepFlatten([1, [2], [[3], 4], 5]); // [1,2,3,4,5]
```

6️⃣ difference
This snippet finds the difference between two arrays.
```js
const difference = (a, b) => {
  const s = new Set(b);
  return a.filter(x => !s.has(x));
};

difference([1, 2, 3], [1, 2, 4]); // [3]
```

7️⃣ differenceBy
This method returns the difference between two arrays, after applying a given function to each element of both lists.
```js
const differenceBy = (a, b, fn) => {
  const s = new Set(b.map(fn));
  return a.filter(x => !s.has(fn(x)));
};

differenceBy([2.1, 1.2], [2.3, 3.4], Math.floor); // [1.2]
differenceBy([{ x: 2 }, { x: 1 }], [{ x: 1 }], v => v.x); // [ { x: 2 } ]
```

8️⃣ differenceWith
This snippet removes the values for which the comparator function returns false.
```js
const differenceWith = (arr, val, comp) => arr.filter(a => val.findIndex(b => comp(a, b)) === -1);

differenceWith([1, 1.2, 1.5, 3, 0], [1.9, 3, 0], (a, b) => Math.round(a) === Math.round(b)); 
// [1, 1.2]
```

9️⃣ digitize
This snippet gets a number as input and returns an array of its digits.
```js
const digitize = n => [...`${n}`].map(i => parseInt(i));

digitize(431); // [4, 3, 1]
```

🔟 distance
This snippet returns the distance between two points by calculating the Euclidean distance.
```jsx
const distance = (x0, y0, x1, y1) => Math.hypot(x1 - x0, y1 - y0);

distance(1, 1, 2, 3); // 2.23606797749979
```

***

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Until next time,
[Abhiraj](https://abhiraj.glitch.me)