adding array chapter readme

Author: crizstian

02-chapter-Arrays.js renamed to 02-chapter-Array/02-chapter-Arrays.js

@@ -15,7 +15,22 @@ class grades {
   }
 }
 
-// ##############################################
+// Implementation of the grade class
+console.log('### Excercise 1');
+const gradeObj = [90,89,75];
+const grade    = new grades(gradeObj);
+grade.addGrade(90);
+grade.addGrade(25);
+console.log(`Avg grade: ${grade.displayAvg()}`);
+
+// #############################################
+console.log('\n### Excercise 2');
+const arrayWords = ["hello ","my ","friend "];
+console.log(`orginal array: ${arrayWords} `);
+console.log(`displaying forward: ${arrayWords.reduce((total, word) => total + word)}`);
+console.log(`displaying backward: ${arrayWords.reduceRight((total, word) => total + word)}`);
+
+// #############################################
 class weekTemps {
 
   constructor(dataStore = []) {
@@ -57,26 +72,7 @@ class weekTemps {
   }
 }
 
-// Excercises
-// #############################################
-console.log('CHAPTER 2');
-console.log('### Excercise 1');
-
-const gradeObj = [90,89,75];
-const grade    = new grades(gradeObj);
-grade.addGrade(90);
-grade.addGrade(25);
-console.log(`Avg grade: ${grade.displayAvg()}`);
-
-// #############################################
-console.log('\n### Excercise 2');
-
-const arrayWords = ["hello ","my ","friend "];
-console.log(`orginal array: ${arrayWords} `);
-console.log(`displaying forward: ${arrayWords.reduce((total, word) => total + word)}`);
-console.log(`displaying backward: ${arrayWords.reduceRight((total, word) => total + word)}`);
-
-// #############################################
+// Implementation of weekTemps class
 console.log('\n### Excercise 3');
 
 const randomMonth = [

02-chapter-Array/readme.md

@@ -0,0 +1,60 @@
+# Array data structure
+
+### Examples
+- [Array exercises and examples codes in ES6](./02-chapter-Arrays.js)
+
+### Definition
+
+The array is the most common data structure in computer programming. Arrays are usually very efficient and are considered good choices for many data storage purposes.
+
+Arrays in JavaScript are very flexible. There are several different ways to create arrays, access array elements, and perform tasks such as searching and sorting the elements stored in an array.
+
+```
+const myArray = [1, 'one', {some: 'object'}, new Date()]
+```
+![](https://docs.oracle.com/javase/tutorial/figures/java/objects-tenElementArray.gif)
+
+### Usage of arrays
+
+**Creating an array**
+
+```
+const grades = [1,2,3];          // this is the best way to create an array.
+const grades = new Array(1,2,3); // use of the constructor.
+const grades = new Array(3);     // will initialize the array with the length of 3.
+grades = [...grades, grade]; 	 // will reinstantiate the grades variable.
+
+// use of the concat() function.
+const a = [1,2,3];
+const b = [4,5,6];
+const c = a.concat(b); // this creates a new array by concatenating the 2 arrays.
+
+```
+or using strings to create an array, by using the ***split*** method and space ' ' delimiter will create a new array containg the words of the text.
+```
+const words = someStringText.split(' ');
+```
+
+**Inserting elements to an array**
+
+There are several ways to add a new element to the array for example:
+
+```
+// This two operations will add a new element at the end of the array.
+grades.push(element);
+grades[grades.length + 1] = grade;
+
+// use of shift() method will insert a new element at the front of the array.
+grades.shift(grade);
+
+//use of the splice() method will insert a new element at the position indicated.
+grades.splice(position, 0, grade);
+```
+The splice() method, has the ability to insert or to remove an element, the first parameter of the method indicates the position, the second parameter indicates the type of operation 0 = insert, 1 = delete, and the third parameter is the new value to insert.
+
+**Deleting elements to an array**
+
+```
+// use of the splice() method.
+grades.splice(position, numElementsToDelete);
+```

README.md

@@ -1,17 +1,16 @@
 # Data Structures and Algorithms with ES6
 
-
 ![](https://i.blogs.es/545cf8/es6-logo/original.png) ![](https://lh3.googleusercontent.com/a4Xrc-8oQLu05mOrNPuvA_o2nZEIEnOoTH4wB91Slw_hCvuIu_Qgi440bK9mC8ml-KA=w300)
 
-This exercises are based from the book [Data Structures and Algorithms with JavaScript](http://shop.oreilly.com/product/0636920029557.do) - [by Michael McMillian (O’Reilly)](http://www.oreilly.com/pub/au/518) ISBN - 978-1-449-36493-9.
+The exercises are based from the book [Data Structures and Algorithms with JavaScript](http://shop.oreilly.com/product/0636920029557.do) - [by Michael McMillian (O’Reilly)](http://www.oreilly.com/pub/au/518) ISBN - 978-1-449-36493-9.
 
-The purpose of this repo is to update the exercises to ES6 standards and to correct the errors from the examples that this book has.
+The purpose of this repo is to update the exercises to ES6 standards and to correct the many errors that the book has.
 
 ## Examples in this repo
 
 | **Num** | **Type** | **Exercises** | **Description** |
 --- | --- | --- | ---
-| 1.- | [Array](./02-chapter-Arrays.js) | 4 | The `Array` is the most common data structure in computer programming
+| 1.- | [Array](./02-chapter-Array) | 4 | The `Array` is the most common data structure in computer programming
 | 2.- | [Lists](./03-chapter-List.js) | 5 | A `List` is an ordered sequence of data, where elements are not meant to be ordered.
 | 3.- | [Stacks](./04-chapter-Stacks.js) | 3 | A `Stack` is an example of Last-in, First-Out (LIFO)
 | 4.- | [Queues](./05-chapter-Queues.js) | 3 | A `Queue` is an example of First-in, First-Out (FIFO)