1. Semicolons are required, always.

// BAD
const name = 'Eduardo'

// GOOD
const name = 'Eduardo';

2. const and let for variable declaration

// BAD
var name = 'Eduardo';
var lastname = 'Peredo';
lastname = 'Rivero';

// GOOD
const name = 'Eduardo';
let lastname = 'Peredo';
lastname = 'Rivero';

3. Prefer map, filter, reduce over forEach as much as you can

// BAD
const values = [1, 2, 3];
let sum = 0;
const greaterThanTwo = [];
const multiplyByTwo = [];

values.forEach(value => {
	sum += value;
});

values.forEach(value => {
	if (value > 2) {
		greaterThanTwo.push(value);
	}
});

values.forEach(value => {
	multiplyByTwo.push(value * 2);
});

// GOOD
const values = [1, 2, 3];
const sum = values.reduce((acum, value) => (acum + value), 0);
const greaterThanTwo = values.filter(value => value > 2);
const multiplyByTwo = values.map(value => value * 2);

4. Use lowerCamelCase notation to write code

// BAD
function GenerateName() {
	const MyName = 'A bad name';
	return MyName;
}

// GOOD
function generateName() {
	const myName = 'Eduardo';
	return myName;
}

5. Use property shorthand all the time

// BAD
const name = 'Eduardo';

const awesomePerson = {
	name: name,
};

// GOOD
const name = 'Eduardo';

const awesomePerson = {
	name,
};

6. Write object properties in alphabetic order ❗️

// BAD
const awesomePerson = {
	weight: 63,
	height: 1.69,
	age: 31,
	name: 'Eduardo',
};

// GOOD
const awesomePerson = {
	age: 31,
	height: 1.69,
	name: 'Eduardo',
	weight: 63,
};

7. Always use arrow-function for anonymous functions

// BAD
axios.get('/users').then(function(res) {
	return res.data;
});

// GOOD
axios.get('/users').then(res => res.data);

8. Use trailing comma always

// BAD
const person = {
	name: 'Eduardo',
	age: 20
};

// GOOD
const person = {
	name: 'Eduardo',
	age: 20,
};

9. Use spread operator for clone/copy objects

// BAD
const myObj = { name: 'Eduardo' };
const newObj = myObj;

// GOOD
const myObj = { name: 'Eduardo' };
const newObj = { ...myObj };

10. Prefer ternary operator for short conditionals

// BAD
if (number > 10) {
	result = isGreatherThanTen();
} else {
	result = isNotGreatherThanTen();
}

// GOOD
result = number > 10 ? isGreatherThanTen() : isNotGreatherThanTen();

11. Use normal function definitions for functions inside objects

// BAD
const person = {
	name: 'Eduardo',
	greeting() {
		return `Hello ${this.name}`;
	},
};

// GOOD

function greeting() {
	return `Hello ${this.name}`;
}

const person = {
	name: 'Eduardo',
	greeting,
};

12. Always define function before they are used

// BAD

const person = {
	name: 'Eduardo',
	greeting,
};

function greeting() {
	return `Hello ${this.name}`;
}

// GOOD

function greeting() {
	return `Hello ${this.name}`;
}

const person = {
	name: 'Eduardo',
	greeting,
};

13. Always put use strict at the start of the file (nodejs only)

// BAD
module.exports = someModule;

// GOOD
'use strict';

module.exports = someModule;

14. Use object/array destructuring as much as you can

// BAD
const person = {
	age: 20,
	name: 'Eduardo',
	weight: 20,
};

const age = person.age;
const name = person.name;
const weight = person.weight;

// GOOD
const person = {
	age: 20,
	name: 'Eduardo',
	weight: 20,
};

const { name, age, weight } = person;

// BAD
const values = [2, 4, 6];
const two = values[0];
const four = values[1];
const six = values[2];

// GOOD
const values = [2, 4, 6];
const [two, four, six] = values;

15. Template literals for concatenate values

// BAD
const name = 'Eduardo';
const lastName = 'P. Rivero';

const fullName = name + lastName;

// GOOD
const name = 'Eduardo';
const lastName = 'P. Rivero';
const fullName = `${name} ${lastname}`;

16. Use Number over parseInt for type casting

// BAD
const ageInString = '30';
const ageInNumber = parseInt(ageInString);

// GOOD
const ageInString = '30';
const ageInNumber = Number(ageInString);

17. Use === to avoid automatic coersion

// BAD
if (value == value2) {
}

// GOOD
if (value === value2) {
}

❗️ = There are exceptions over this rule