Coding diary to reflect concepts that I am learning and revisiting

1. Combining filter (array method) and .length to find the total number of elements that are above or below a certain value

(E.g. Given an array of different ages. Find the total number of people that are above the age of 21)

/**
* @param {number[]} ages
*/

const numOfEligibleVoters = ages => {
	let total = 0;
	ages.forEach(age => {
		if (age >= 21) {
			total += 1;
		}
	})
	return total;
}

Using Filter + length

/**
* @param {number[]} ages
*/

const numOfEligibleVoters = ages => {
	return ages.filter(ages => age >= 21).length
}

2. The find() array method

3. Classes in Js (Syntax recap + elementary concept refresher)

Creating a new instance of a class

const person1 = new Person("Anne Smith");
// person1 is the variable for the instance of the class Person

The this keyword

• Inside of the instance method, the "this" keyword refers to the current instance of the class

Basic Constructor syntax

class Person {
	constructor(firstName, lastName) {
	this.firstName = firstName;
	this.lastName = lastName;
	}

	fullName() {
		return `${this.firstName} ${this.lastName}`;
	}
	sayHi() {
		// calling the instance method
		const name = this.fullName();
		return `Hi ${name}`
	}
}

If you want an instance method to call another instance method use the following syntax: this.nameOfFunction()

Setters and Getters

• Underscore syntax "_" --> a convention used to denote that the property is internal to the class and should not accessed from outside