Зміст курсу

JavaScript Data Structures

1. Introduction and Prerequisites

Introduction to the Course Prerequisites for the Course What Will Be Covered Tips for Success

2. Objects Fundamentals

Understanding Objects Object Creation Nested Properties Challenge: Creating an Object Accessing Object Properties Challenge: Accessing Object Properties Working with Properties Challenge: Modifying and Extending Object Object Methods Properties in Methods Challenge: Working with Object Methods Object Fundamentals Sum Up

3. Advanced Object Manipulation

Object Iteration with for...in Loop Challenge: Object Property Explorer Method hasOwnProperty()Challenge: hasOwnProperty() for Object Property Iteration Spread Operator Challenge: Merging Objects and Adding Properties Object Destructuring Challenge: Destructuring Advanced Object Manipulation Sum Up

4. Mastering Arrays

Understanding Arrays Challenge: Array Element Accessor Working with Array Elements Challenge: Array Element Modifier for Loop Challenge: Array Element Iteration for...of Loop Challenge: Iteration with for...of Mastering Arrays Sum Up

5. Advanced Array Operations

map() Method Challenge: Array Element Transformation filter() Method Challenge: Filtering Students by Exam Scores find() Method Challenge: Discovering Featured Products sort() Method Challenge: Sorting and Extracting Properties Advanced Array Operations Sum Up Course Sum Up

JavaScript Data Structures

map() Method

This section will explore several commonly used methods for working with arrays in JavaScript. JS offers a wide variety of methods, but we will focus specifically on those that prove invaluable in everyday programming: map(), filter(), find(), reduce(), and sort(). These methods are chosen for practical utility, addressing common scenarios encountered in coding tasks.

For a comprehensive list of all array methods, you can refer to the official MDN documentation.

map()

The map() method iterates over each element of the original array and applies a specified callback function to produce a new array.

Here's the basic syntax:

element: This is the current element being processed in the array;
index: This is the current element's index within the array. It represents the position of the element in the array;
array: This is the array on which the map() method was called. It refers to the original array being iterated over.

Let's illustrate what element, index, and array represent:

Key points to remember about the map():

It iterates over the original array element by element;
It does not modify the original array;
The callback function's result is used to create a new array;
It returns a new array of the same length.

Transforming Array Elements

The map() method shines when we need to transform every element of an array without modifying the original array. Consider the following example:

Code Description

Line 1: Here, an array named numbers is created with five numeric elements.
Lines 5-7: The map method is used on the numbers array. This method creates a new array (doubledNumbers) by applying a provided function to each element of the original array (numbers). In this case, the provided function takes each element (element) and multiplies it by 2. So, for the numbers array, it doubles each element, resulting in the doubledNumbers array.
Lines 9-10: The console.log statements are used to output the content of the numbers array and the modified doubledNumbers array to the console.

1. What does the `map()` method do?

2. What is a key characteristic of the `map()` method?

3. In the example below, what does the `strings.map((element) => (element += "!"))` do?

Все було зрозуміло?

Секція 5. Розділ 1

Зміст курсу

JavaScript Data Structures

1. Introduction and Prerequisites

Introduction to the Course Prerequisites for the Course What Will Be Covered Tips for Success

2. Objects Fundamentals

3. Advanced Object Manipulation

4. Mastering Arrays

5. Advanced Array Operations

JavaScript Data Structures

map() Method

For a comprehensive list of all array methods, you can refer to the official MDN documentation.

map()

The map() method iterates over each element of the original array and applies a specified callback function to produce a new array.

Here's the basic syntax:

element: This is the current element being processed in the array;
index: This is the current element's index within the array. It represents the position of the element in the array;
array: This is the array on which the map() method was called. It refers to the original array being iterated over.

Let's illustrate what element, index, and array represent:

Key points to remember about the map():

It iterates over the original array element by element;
It does not modify the original array;
The callback function's result is used to create a new array;
It returns a new array of the same length.

Transforming Array Elements

The map() method shines when we need to transform every element of an array without modifying the original array. Consider the following example:

Code Description

1. What does the `map()` method do?

2. What is a key characteristic of the `map()` method?

3. In the example below, what does the `strings.map((element) => (element += "!"))` do?

Все було зрозуміло?

Секція 5. Розділ 1