Key Differences between Python and JavaScript

Python and JavaScript are important languages used in web development. Python can be used for backend development while JavaScript is used for both frontend and backend development. This article will analyze the key differences between these two languages. <!--more-->

Real world application of Python and JavaScript #

Python can be used in scientific and specialized applications, as well as in web development. However, JavaScript is widely used in web development.

Syntax, sentactical and functional differences #

Python and JavaScript have different Syntax.

This is demonstrated below:

Code blocks in Python and JavaScript #

In Python, lines of code are put in blocks through indentation.

Example

if  t  > 10:       
     print (t) #code block

In JavaScript, brackets can be utilized rather than spaces.

Let's look at an example.

if (t>10)

{
    console.log(t)
}

Definition of variables #

When defining a variable in Python, a variable name is written followed by an equal (=) sign.

Then a value is assigned to the variable. i.e:

<variable_name> = value
x = 56

In JavaScript, a keyword var is added before the variable name and a semicolon is used to terminate the statement i.e:

var <variable_name>  = value;
var k=34;

Variable naming conventions #

In Python, the snake_case naming style is used. The names should be in lowercase and separated by an underscore, as shown below.

first_name

In JavaScript, lowerCamelCase is preferred. The variable name starts with a lowercase letter and every other new word starts with an uppercase letter.

myFirstName

Constants in Python and JavaScript #

In Python, constants are written in uppercase format separated by an underscore. Such as CONSTANT_NAME.

For example:

PASS_RATE = 4

In JavaScript, a keyword const is added before the constant name and a semicolon is used to terminate the statement. ie. const CONSTANT_NAME = value;

const AGE=56;

Data types and values in Python and JavaScript #

Numeric data types #

In Python, we have three numeric types that will assist us with accomplishing exact estimations for logical purposes.

These are:

1. int.
2. float.
3. complex.

In JavaScript, we have two numeric types, Numbers and BigInt. The two whole numbers and casting point numbers are just viewed as numbers.

1. numbers
2. bigint

None and Null in Python and JavaScript #

In Python, when a variable doesn't have an assigned value, it is referred to as None. In JavaScript, we use null for such variables.

The undefined value #

In Python, one cannot declare a variable without an initial value.

In Javascript, we have a unique worth that is allocated consequently. When a variable is declared without assigning an initial value, it prints out undefined, as shown below:

var k; // should print undefined

Primitive data types #

Python has four primitive data types:

1. Integers.
2. Float.
3. Boolean.
4. Strings.

On the other hand, JavaScript has six primitive data types:

1. undefined.
2. strings.
3. Number.
4. BigInt.
5. Boolean.
6. symbol.

Comments #

Comments help to improve code readability. For example, one may comment on a line for future reference. <!--A commented line is not executed as part of the code. -->

1. Single-line comments In Python, a hashtag (#) is used to comment on a single line.

# this is a  single-line comment in python

In JavaScript, double slashes (//) are used to comment on a single line, as shown below.

//this is a single-line comment in JavaScript

2. Multiple line comments These are comments spanning many lines. When writing multiple comments in python, we start every single line with a hashtag (#) as shown below:

# this is a   
# multiple lines 
# comment
# as used in Python`

When writing multiple line comments in JavaScript, we use symbols (/*) to open and (*/) to close a comment:

/*
 This is  a multi-line comment
that span many lines
*/ 

Built-in data structures #

1. Tuples Tuples in Python are similar to lists but immutable. They store information that should not be changed.

In JavaScript, we don't have an inherent construction with such qualities.

2. List and Arrays-->

Lists are utilized in python to store a progression of qualities in a similar structure.

number = [3, 4,5]

An array is the equivalent version of this in JavaScript.

var number = [3,4,5]

Comparing values and types #

In Python, the double equal (==) operator is used to compare if two values and their data types are equal.

11 == 11 #True
11 == 10 #False

As shown above, 11 == 11 is true, while 11 == 10 is false.

In JavaScript, a triple equivalent ('===') operator is utilized to check if two qualities and their information types are equivalent.

5===5  //true
5==='5'  //false

Logical operators #

In Python, there are three logical operators:

1. and
2. or
3. not

JavaScript also has three logical operators:

1. && -- logical and.
2. || -- logical or.
3. ! --logical not.

Type operators #

To check the object type in Python, we use the (type()) function as shown below:

type(instance)

To check the type of object in JavaScript we use type of operator, as highlighted below:

type of instance

Inputs and outputs #

Input is a function that requests the user for some feedback.

Output, on the other hand, is used to print out a specific message.

Inputs #

In Python, the input() function is used to ask for user input.

Example

name = input (" Enter your name : ")

In JavaScript, you can get the user's input using a small prompt with window.prompt(message) and then assign the result to a variable.

var input =window.prompt ("enter a Number :")

Outputs #

In Python, we use the print() to show particular results.

Example

num1 = input("Enter the first  number : ")
num2 = input("Enter a second  number : ")
num3 = input("Enter a third number : ")
result = num1 + num2 + num3
print(result)

In JavaScript, we print a value in the console using the console.log() function and parse the values within the parenthesis.

Example

console.log("My name is John:");

Conditional statements #

Conditional statements are used to act if a certain condition is true or false.

1. if statement In Python, indentation is relied upon to indicate the lines of code that belong to a conditional statement.

if condition:
     #code

Let's look at an example:

age = 10
if age < 18:
    print('kid you are!')

In JavaScript, the condition is enclosed in parenthesis and the code enclosed within curly braces:

if (condition)

    {
        code
    }

An example of a JavaScript codesnippet would look like:

if (hour > 4) {
  task = "Clean the compound";
}

2. if-else statement In Python, a colon (:) is written after the else keyword.

if condition:

    #if code

else :

    #else code

Let's look at an example:

age = 34
if age < 18:
    print('kid you are!')
else:
    print('You are not a kid')

In JavaScript, the code that belongs to the else clause is enclosed in curly braces.

if (condition)

    {
        if code
    }

else 

    {
        else code
    }

Let's look at an example.

var time = new Date().getHours();
if (time < 5) {
  task = "Cleaning the house";
} else {
  task = "Feeding the sheep";
}

3. Multiple conditions In Python, elif keyword is used when dealing with multiple conditions. After every condition we write a semicolon``(:) and the code that belongs to the condition is indented in the next line.

if condition1:

    code

elif condition2:

    code

elif condition3:

    code

else:

    code

Let's look at an example.

age = 40
if age < 18:
    print('kid you are!')
elif age >=18 and age < 29:
    print('You are a young star!')
elif age >=29 and age < 35:
    print('You are middle aged!')
else:
    print('You are above middle age !')

In JavaScript, the else if keyword is used when dealing with multiple conditions. The conditions are surrounded by parenthesis.

if(condition1)

    {
        //code
    }

else if(condition2)

    {
       // code
    }

else if (condition3)

    {
        //code
    }

else

    {
        //code
    }

Let's look at an example.

var time = new Date().getHours();
if (time < 5) {
  task = "Cleaning the house";
} else if (time < 15) {
  task = "Feeding the sheep";
} else {
  task = "Watching a movie";
}

4. Switch Python does not have this type of built-in control structure i.e switch

In JavaScript, a switch is utilized to pick what happens depending on user specification.

switch(expression)

    {
        case 1:
        code
        break;

        case 2:
        code
        break;

        case 3:
        code
        break;

        default:
        code
    }

Let's look at an example.

switch (new Month().getMonth()) {
  case 1:
    month = "January";
    break;
  case 2:
    month = "April";
    break;
  case 3:
    month = "May";
    break;
  case 4:
    month = "June";
    break;
  case 5:
    month = "August";
    break;
  case 6:
    month = "September";
    break;
  default:
  No such a month;
}    

Loops #

A loop is a control structure that repeats a series of instructions until a specified condition is reached.

For Loops #

We can write a for loop in Python as shown below.

for x in range(k):

    code

The syntax when writing a for loop in JavaScript is as follows.

for(var x = 1; x >n ; x++)

{

        code
}

While loop #

It is a pre-test loop in which the condition is evaluated before the loop executes.

In Python, we compose the watchword while trailed by the condition, and afterward, a colon (:).

while condition: code 

In JavaScript, we use brackets, as shown below.

while(condition){
    code
}

Do-while loops #

This is a post-test loop. The condition is evaluated after the loop executes. In Python, we do not have such a control structure (do-while loop)

In JavaScript, this loop will always be executed once.

do { code } while (condition); 

Functions #

A function is a block of code that plays out a specific undertaking.

In Python, we utilize a watchword def which is trailed by the name of the function, as demonstrated below:

 def function_name ( x1 , x2 , x3 , ...):
      code 

In JavaScript, we use the function keyword to create a method.

function function_name (x1,x2,x3,...)
        {

            code
        }

Object Oriented Programming (OOP) #

OOP is the development of programs in terms of objects that interact with one another.

Both Python and JavaScript support Object-Oriented programming.

The syntax of defining a class in both Python and JavaScript is almost the same, there only is a slight difference.

In Python a colon is written after the keyword class whereas curly braces are used in Javascript.

Python

class Rectangle:

    code

JavaScript

class Rectangle

{

    code
}

Constructor and attributes #

A constructor is a member function of a class that executes automatically whenever an object is created.

In Python, a constructor that instantiates the new example is known as init with two driving and the following highlights.

 class Rectangle:

        def _init _(self , length , width):
            self.length= length
            self.width=width 

In JavaScript, a constructor is written, as shown below:

class Rectangle

{

    constructor(length,width){
        this.length=length;
        this.width=width;

    }
}

Note: In python, we use self to refer to an instance of a class.

For example:

self.attribute= esteem 

While in JavaScript we use this to allude to an occurrence of a class. Such as:

this.attribute=value; 

Conclusion #

Although Python and JavaScript have numerous differences, Python is much easier to understand than JavaScript due to its unique syntax.

Happy coding!

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Peer Review Contributions by: Wanja Mike