4.14 Prototypes Part 3¶

Modifying Constructors 2¶

Task 1: Delete the fullName method from the User.prototype below. Hint: use delete User.prototype.fullName

function User(fstName, lstName){
  this.firstName = fstName;
  this.lastName = lstName;
}

User.prototype.fullName = function(){
  return (this.firstName + " " + this.lastName);
}
console.log(User.prototype);

console.log(".................")

delete User.prototype.fullName;
console.log(User.prototype);

The result is as follows:

{fullName: ƒ, constructor: ƒ}
.................
{constructor: ƒ}

Task 2: Delete the languageVerbose method from the Epic.prototype below.

function Epic(name, author, lang){
  this.name = name;
  this.author = author;
  this.language = lang;
}

Epic.prototype.languageVerbose = function(){
    return `${this.name} was written in ${this.language}.`
}
console.log(Epic.prototype);
console.log(".............................")
delete Epic.prototype.languageVerbose;
console.log(Epic.prototype);

The result is as follows:

{languageVerbose: ƒ, constructor: ƒ}
.............................
{constructor: ƒ}

Task 3: Delete the category property from the Video.prototype below.

function Video(title, lang){
  this.title = title;
  this.language = lang;
}

Video.prototype.category = "Education";
console.log(Video.prototype);
console.log(".....................")
delete Video.prototype.category;
console.log(Video.prototype);

The result is as follows:

{category: "Education", constructor: ƒ}
.....................
{constructor: ƒ}

Task 4: Delete the brand property from the MarkerPen.prototype below.

function MarkerPen(color, price){
  this.color = color;
  this.price = price;
}

MarkerPen.prototype.brand = "Claro";
console.log(MarkerPen.prototype);
console.log(".....................")
delete MarkerPen.prototype.brand;
console.log(MarkerPen.prototype);

The result is as follows:

{brand: "Claro", constructor: ƒ}
.....................
{constructor: ƒ}

Task 5: Delete the course property from the Section.prototype below.

function Section(title, desc){
    this.title = title;
    this.description = desc;
}

Section.prototype.course = "JavaScript Course";
console.log(Section.prototype);
console.log(".....................")
delete Section.prototype.course;
console.log(Section.prototype);

The result is as follows:

{course: "JavaScript Course", constructor: ƒ}
.....................
{constructor: ƒ}

Extra Practice¶

Task 6: Build a lesson constructor. Hint: Use the below lesson object.

/*
var lesson = {
  title: null,
  difficultyLevel: null
};
*/

function Lesson(title, diffLev){
  this.title = title;
  this.difficultyLevel = diffLev;
}

Task 7: Refer to task 6; add section property to Lesson.prototype. Set the section value to Section 1.

function Lesson(title, diffLev){
  this.title = title;
  this.difficultyLevel = diffLev;
}

Lesson.prototype.section = "Section 1";
console.log(Lesson.prototype);

The result is: {section: "Section 1", constructor: ƒ}

Task 8: Refer to task 7; add about method to Lesson.prototype. Set the about value to {title} is {difficultyLevel} and it comes under {section} discussion

function Lesson(title, diffLev){
  this.title = title;
  this.difficultyLevel = diffLev;
}

Lesson.prototype.section = "Section 1";
Lesson.prototype.about = function(){
  return `The difficulty level of ${this.title} is ${this.difficultyLevel} and it comes under ${this.section} discussion.`;
}

var lesson1 = new Lesson("Array Helpers", "Normal");
var lesson2 = new Lesson("Objects", "Easy");

console.log(lesson1.about());
console.log(lesson2.about());

The result is as follows:

The difficulty level of Array Helpers is Normal and it comes under Section 1 discussion.
The difficulty level of Objects is Easy and it comes under Section 1 discussion.

Task 9: Refer to task 8; display all the added properties and methods to the lesson.prototype.

function Lesson(title, diffLev){
  this.title = title;
  this.difficultyLevel = diffLev;
}

Lesson.prototype.section = "Section 1";
Lesson.prototype.about = function(){
  return `The difficulty level of ${this.title} is ${this.difficultyLevel} and it comes under ${this.section} discussion.`;
}

for (var prop in Lesson.prototype){
  console.log(`${prop}:${Lesson.prototype[prop]}`);
}

The result is as follows:

section:Section 1
about:function(){
  return `The difficulty level of ${this.title} is ${this.difficultyLevel} and it comes under ${this.section} discussion.`;
}

Task 10: Refer to Task 9; delete about method from Lesson.prototype.

function Lesson(title, diffLev){
  this.title = title;
  this.difficultyLevel = diffLev;
}

Lesson.prototype.section = "Section 1";
Lesson.prototype.about = function(){
  return `The difficulty level of ${this.title} is ${this.difficultyLevel} and it comes under ${this.section} discussion.`;
}

for (var prop in Lesson.prototype){
  console.log(`${prop}:${Lesson.prototype[prop]}`);
}
console.log("......................");
delete Lesson.prototype.about;
for (var prop in Lesson.prototype){
  console.log(`${prop}:${Lesson.prototype[prop]}`);
}

The result is as follows:

section:Section 1
about:function(){
  return `The difficulty level of ${this.title} is ${this.difficultyLevel} and it comes under ${this.section} discussion.`;
}
......................
section:Section 1

Task 11: Build a quote constructor. Hint: Use the below quote object.

/*
var quote = {
  author: null,
  source: null,
  theWord: null
};
*/

function Quote(author, src, word){
  this.author = author;
  this.source = src;
  this.theWord = word;
}

Task 12: Refer to task 11; add date property to Quote.prototype. Set the date value to Date.now().

function Quote(author, src, word){
  this.author = author;
  this.source = src;
  this.theWord = word;
}

Quote.prototype.date = Date.now();

console.log(Quote.prototype);

The result is: {date: 1601195465160, constructor: ƒ}

Task 13: Refer to task 12; add mentions property to Quote.prototype. Set the mentions value to ["book1", "book2", "book3"].

function Quote(author, src, word){
  this.author = author;
  this.source = src;
  this.theWord = word;
}

Quote.prototype.date = Date.now();
Quote.prototype.mentions = ["book1", "book2", "book3"];

console.log(Quote.prototype);

The result is: {date: 1601195642503, mentions: Array(3), constructor: ƒ}

Task 14: Refer to task 13; add category property to Quote.prototype. Set the category value to religious.

function Quote(author, src, word){
  this.author = author;
  this.source = src;
  this.theWord = word;
}

Quote.prototype.date = Date.now();
Quote.prototype.mentions = ["book1", "book2", "book3"];
Quote.prototype.category = "religious";

console.log(Quote.prototype);

The result is: {date: 1601195713013, mentions: Array(3), category: "religious", constructor: ƒ}

Task 15: Refer to task 14; display all the added properties and methods to the Quote.prototype.

function Quote(author, src, word){
  this.author = author;
  this.source = src;
  this.theWord = word;
}

Quote.prototype.date = Date.now();
Quote.prototype.mentions = ["book1", "book2", "book3"];
Quote.prototype.category = "religious";

for (var prop in Quote.prototype){
  console.log(`${prop}:${Quote.prototype[prop]}`);
}

The result is as follows:

date:1601195806427
mentions:book1,book2,book3
category:religious

Task 16: Refer to task 15; delete category property from Quote.prototype.

function Quote(author, src, word){
  this.author = author;
  this.source = src;
  this.theWord = word;
}

Quote.prototype.date = Date.now();
Quote.prototype.mentions = ["book1", "book2", "book3"];
Quote.prototype.category = "religious";

for (var prop in Quote.prototype){
  console.log(`${prop}:${Quote.prototype[prop]}`);
}
console.log(".......");

delete Quote.prototype.category;
for (var prop in Quote.prototype){
  console.log(`${prop}:${Quote.prototype[prop]}`);
}

The result is as follows:

date:1601195925683
mentions:book1,book2,book3
category:religious
.......
date:1601195925683
mentions:book1,book2,book3