Monday, April 3, 2023

Lesson 2 (Data Types in JavaScript)

Learning JavaScript as a Second Language

Number

Declaring Integer type variable in JavaScript :-

var x = 23;

let x = 20;

Declaring Floating point value in JavaScript :-

var x = 5.78945146;

console.log(x.toFixed(2));

Output: "5.78"

5.789.toFixed(2) would return a value of String type.

JavaScript has a single number type. Internally, it is represented as 64-bit floating point, the same as Java’s double. Unlike most other programming languages, there is no separate integer type, so 1 and 1.0 are the same value. This is a significant convenience because problems of overflow in short integers are completely avoided, and all you need to know about a number is that it is a number. A large class of numeric type errors is avoided.

Ref: Douglas Crockford - JavaScript. The Good Parts (2008)

Comparing int and float in JavaScript

Comparing int and float in Python

Math library of JavaScript
Ref: Math Module Reference

Strings

Declaring String variable in JavaScript :-

// Using string template

var variable = “Gokul Krishna”

// Using String class

var variable = new String(“Gokul Krishna”);

String Concatenation

Ref: https://www.w3schools.com/jsref/jsref_obj_string.asp

Boolean in JavaScript

let x = true;

let y = false;

let result = x.toString();

console.log(result);

In Python:

Arrays in Code

var arr_num = [1, 2, 3, 0, -5, -2]

let arr_names = ['Dip', 'Gokul', 'Krishna', 'Ashish']

let arr_of_mixed_types = [1, 'Krishna', true]

/* To name a few operations that we can do on an array:

(1) Traversing or 'Iterating over the elements of an array' (2) Sort (3) Search (4) Insertion (5) Deletion (6) Reversing */

console.log(arr_num)

console.log(arr_num.sort()) // Changes the actual object. Return type: modified array.

console.log(arr_num.reverse()) // Changes the actual object.

// These operations sort() and reverse() change the actual object.

// The push() method adds new items to the end of an array.

arr_num.push(10)