This content originally appeared on DEV Community and was authored by Abhiraj Bhowmick
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.
1️⃣ average
This snippet returns the average of two or more numerical values.
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.
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.
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.
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.
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.
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.
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.
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.
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.
const distance = (x0, y0, x1, y1) => Math.hypot(x1 - x0, y1 - y0);
distance(1, 1, 2, 3); // 2.23606797749979
Thank you for reading. Hope this has been of some help to you.
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Until next time,
Abhiraj
This content originally appeared on DEV Community and was authored by Abhiraj Bhowmick
Abhiraj Bhowmick | Sciencx (2021-11-24T12:45:58+00:00) Javascript snippets you need to know right now 🔥 – #3. Retrieved from https://www.scien.cx/2021/11/24/javascript-snippets-you-need-to-know-right-now-%f0%9f%94%a5-3/
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