Background Context

JavaScript is used for many things. Here, you will use JavaScript for 2 reasons:

Scripting (same as we did with Python)
Web front-end

For the moment, and for learning all basic concepts of this language, we will do some scripting. After, we will make our AirBnB project dynamic by using Javascript and JQuery.

Resources

Read or watch:

Writing JavaScript Code
Variables
Data Types
Operators
Operator Precedence
Controlling Program Flow
Functions
Objects and Arrays
Intrinsic Objects
Module patterns
var, let and const
JavaScript Tutorial
Modern JS

Learning Objectives

At the end of this project, you are expected to be able to explain to anyone, without the help of Google:

General

Why JavaScript programming is amazing
How to run a JavaScript script
How to create variables and constants
What are differences between var, const and let
What are all the data types available in JavaScript
How to use the if, if ... else statements
How to use comments
How to affect values to variables
How to use while and for loops
How to use break and continue statements
What is a function and how do you use functions
What does a function that does not use any return statement return
Scope of variables
What are the arithmetic operators and how to use them
How to manipulate dictionary
How to import a file

Requirements

General

Allowed editors: vi, vim, emacs
All your files will be interpreted on Ubuntu 20.04 LTS using node (version 14.x)
All your files should end with a new line
The first line of all your files should be exactly #!/usr/bin/node
A README.md file, at the root of the folder of the project, is mandatory
Your code should be semistandard compliant (version 16.x.x). Rules of Standard + semicolons on top. Also as reference: AirBnB style
All your files must be executable
The length of your files will be tested using wc

More Info

Install Node 14

$ curl -sL https://deb.nodesource.com/setup_14.x | sudo -E bash -
$ sudo apt-get install -y nodejs

Install semi-standard

Documentation

$ sudo npm install semistandard --global

Quiz questions

Question #0

Does Javascript have String as a native datatype?

No
Yes

Question #1

Does Javascript have Dictionary as a native datatype?

No
Yes

Tips:

Everything is Object and Object type in Javascript is powerful.

Question #2

Does Javascript have Array as a native datatype?

No
Yes

Question #3

Does Javascript have Set as a native datatype?

No
Yes

Question #4

What does let mean? (please check all true answers)

It’s the keyword to define a variable that can be re-assign during the execution
It’s the keyword to define a variable in the local scope
It’s the keyword to define a global variable
It’s the keyword to define a constant variable
It’s the keyword to define a variable with optionally initializing it to a value

Question #5

What does const mean? (please check all true answers)

It’s the keyword to define a variable that can be re-assign during the execution
It’s the keyword to define a variable in the local scope
It’s the keyword to define a global variable
It’s the keyword to define a constant variable
It’s the keyword to define a variable with optionally initializing it to a value

Tasks

0. First constant, first print

Write a script that prints “JavaScript is amazing”:

You must create a constant variable called myVar with the value “JavaScript is amazing”
You must use console.log(...) to print all output
You are not allowed to use var

guillaume@ubuntu:~/0x12$ ./0-javascript_is_amazing.js
JavaScript is amazing
guillaume@ubuntu:~/0x12$
guillaume@ubuntu:~/0x12$ semistandard ./0-javascript_is_amazing.js
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 0-javascript_is_amazing.js

1. 3 languages

Write a script that prints 3 lines:

The first line: “C is fun”
The second line: “Python is cool”
The third line: “JavaScript is amazing”
You must use console.log(...) to print all output
You are not allowed to use var

guillaume@ubuntu:~/0x12$ ./1-multi_languages.js
C is fun
Python is cool
JavaScript is amazing
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 1-multi_languages.js

2. Arguments

Write a script that prints a message depending of the number of arguments passed:

If no arguments are passed to the script, print “No argument”
If only one argument is passed to the script, print “Argument found”
Otherwise, print “Arguments found”
You must use console.log(...) to print all output
You are not allowed to use var

Reference: process.argv

guillaume@ubuntu:~/0x12$ ./2-arguments.js
No argument
guillaume@ubuntu:~/0x12$ ./2-arguments.js Best
Argument found
guillaume@ubuntu:~/0x12$ ./2-arguments.js Best School
Arguments found
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 2-arguments.js

3. Value of my argument

Write a script that prints the first argument passed to it:

If no arguments are passed to the script, print “No argument”
You must use console.log(...) to print all output
You are not allowed to use var
You are not allowed to use length

guillaume@ubuntu:~/0x12$ ./3-value_argument.js
No argument
guillaume@ubuntu:~/0x12$ ./3-value_argument.js School
School
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 3-value_argument.js

4. Create a sentence

Write a script that prints two arguments passed to it, in the following format: “ is ”

You must use console.log(...) to print all output
You are not allowed to use var

guillaume@ubuntu:~/0x12$ ./4-concat.js c cool
c is cool
guillaume@ubuntu:~/0x12$ ./4-concat.js c
c is undefined
guillaume@ubuntu:~/0x12$ ./4-concat.js
undefined is undefined
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 4-concat.js

5. An Integer

Write a script that prints My number: <first argument converted in integer> if the first argument can be converted to an integer:

If the argument can’t be converted to an integer, print “Not a number”
You must use console.log(...) to print all output
You are not allowed to use var
You are not allowed to use try/catch

guillaume@ubuntu:~/0x12$ ./5-to_integer.js
Not a number
guillaume@ubuntu:~/0x12$ ./5-to_integer.js 89
My number: 89
guillaume@ubuntu:~/0x12$ ./5-to_integer.js "89"
My number: 89
guillaume@ubuntu:~/0x12$ ./5-to_integer.js 89.89
My number: 89
guillaume@ubuntu:~/0x12$ ./5-to_integer.js School
Not a number
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 5-to_integer.js

6. Loop to languages

Write a script that prints 3 lines: (like 1-multi_languages.js) but by using an array of string and a loop

The first line: “C is fun”
The second line: “Python is cool”
The third line: “JavaScript is amazing”
You must use console.log(...) to print all output
You are not allowed to use var
You are not allowed to use any if/else statement
You can use only one console.log
You must use a loop (while, for, etc.)

guillaume@ubuntu:~/0x12$ ./6-multi_languages_loop.js
C is fun
Python is cool
JavaScript is amazing
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 6-multi_languages_loop.js

7. I love C

Write a script that prints x times “C is fun”

Where x is the first argument of the script
If the first argument can’t be converted to an integer, print “Missing number of occurrences”
You must use console.log(...) to print all output
You are not allowed to use var
You can use only two console.log
You must use a loop (while, for, etc.)

guillaume@ubuntu:~/0x12$ ./7-multi_c.js 2
C is fun
C is fun
guillaume@ubuntu:~/0x12$ ./7-multi_c.js 5
C is fun
C is fun
C is fun
C is fun
C is fun
guillaume@ubuntu:~/0x12$ ./7-multi_c.js
Missing number of occurrences
guillaume@ubuntu:~/0x12$ ./7-multi_c.js -3
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 7-multi_c.js

8. Square

Write a script that prints a square

The first argument is the size of the square
If the first argument can’t be converted to an integer, print “Missing size”
You must use the character X to print the square
You must use console.log(...) to print all output
You are not allowed to use var
You must use a loop (while, for, etc.)

guillaume@ubuntu:~/0x12$ ./8-square.js
Missing size
guillaume@ubuntu:~/0x12$ ./8-square.js School
Missing size
guillaume@ubuntu:~/0x12$ ./8-square.js 2
XX
XX
guillaume@ubuntu:~/0x12$ ./8-square.js 6
XXXXXX
XXXXXX
XXXXXX
XXXXXX
XXXXXX
XXXXXX
guillaume@ubuntu:~/0x12$ ./8-square.js -3
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 8-square.js

9. Add

Write a script that prints the addition of 2 integers

The first argument is the first integer
The second argument is the second integer
You have to define a function with this prototype: function add(a, b)
You must use console.log(...) to print all output
You are not allowed to use var

guillaume@ubuntu:~/0x12$ ./9-add.js
NaN
guillaume@ubuntu:~/0x12$ ./9-add.js 1
NaN
guillaume@ubuntu:~/0x12$ ./9-add.js 1 7
8
guillaume@ubuntu:~/0x12$ ./9-add.js 13 89
102
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 9-add.js

10. Factorial

Write a script that computes and prints a factorial

The first argument is integer (argument can be cast as integer) used for computing the factorial
Factorial of NaN is 1
You must do it recursively
You must use a function
You must use console.log(...) to print all output
You are not allowed to use var

guillaume@ubuntu:~/0x12$ ./10-factorial.js
1
guillaume@ubuntu:~/0x12$ ./10-factorial.js 3
6
guillaume@ubuntu:~/0x12$ ./10-factorial.js 89
1.6507955160908452e+136
guillaume@ubuntu:~/0x12$ ./10-factorial.js 333
Infinity
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 10-factorial.js

11. Second biggest!

Write a script that searches the second biggest integer in the list of arguments.

You can assume all arguments can be converted to integer
If no argument passed, print 0
If the number of arguments is 1, print 0
You must use console.log(...) to print all output
You are not allowed to use var

guillaume@ubuntu:~/0x12$ ./11-second_biggest.js
0
guillaume@ubuntu:~/0x12$ ./11-second_biggest.js 1
0
guillaume@ubuntu:~/0x12$ ./11-second_biggest.js 4 2 5 3 0 -3
4
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 11-second_biggest.js

12. Object

Update this script to replace the value 12 with 89:

You are not allowed to use var

guillaume@ubuntu:~/0x12$ cat 12-object.js
#!/usr/bin/node
const myObject = {
  type: 'object',
  value: 12
};
console.log(myObject);
/*
YOUR CODE HERE
*/
console.log(myObject);

guillaume@ubuntu:~/0x12$ ./12-object.js
{ type: 'object', value: 12 }
{ type: 'object', value: 89 }
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 12-object.js

13. Add file

Write a function that returns the addition of 2 integers.

The function must be visible from outside
The name of the function must be add
You are not allowed to use var

Tip

guillaume@ubuntu:~/0x12$ cat 13-main.js
#!/usr/bin/node
const add = require('./13-add').add;
console.log(add(3, 5));
guillaume@ubuntu:~/0x12$ ./13-main.js
8
guillaume@ubuntu:~/0x12

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 13-add.js

14. Const or not const

Write a file that modifies the value of myVar to 333

guillaume@ubuntu:~/0x12$ cat 100-main.js
#!/usr/bin/node
myVar = 89;
require('./100-let_me_const')
console.log(myVar);
guillaume@ubuntu:~/0x12$ ./100-main.js
333
guillaume@ubuntu:~/0x12$

Do you get it? Talk about it!

Hint: Scope

This exercise doesn’t pass semistandard so don’t worry about it.

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 100-let_me_const.js

15. Call me Moby

Write a function that executes x times a function.

The function must be visible from outside
Prototype: function (x, theFunction)
You are not allowed to use var

guillaume@ubuntu:~/0x12$ cat 101-main.js
#!/usr/bin/node
const callMeMoby = require('./101-call_me_moby').callMeMoby;
callMeMoby(3, function () {
  console.log('C is fun');
});
guillaume@ubuntu:~/0x12$ ./101-main.js
C is fun
C is fun
C is fun
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 101-call_me_moby.js

16. Add me maybe

Write a function that increments and calls a function.

The function must be visible from outside
Prototype: function (number, theFunction)
You are not allowed to use var

guillaume@ubuntu:~/0x12$ cat 102-main.js
#!/usr/bin/node
const addMeMaybe = require('./102-add_me_maybe').addMeMaybe;
addMeMaybe(4, function (nb) {
  console.log('New value: ' + nb);
});
guillaume@ubuntu:~/0x12$ ./102-main.js
New value: 5
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 102-add_me_maybe.js

17. Increment object

Update this script by adding a new function incr that increments the integer value.

You are not allowed to use var

guillaume@ubuntu:~/0x12$ cat 103-object_fct.js
#!/usr/bin/node
const myObject = {
  type: 'object',
  value: 12
};
console.log(myObject);
/*
YOUR CODE HERE
*/
myObject.incr();
console.log(myObject);
myObject.incr();
console.log(myObject);
myObject.incr();
console.log(myObject);

guillaume@ubuntu:~/0x12$ ./103-object_fct.js
{ type: 'object', value: 12 }
{ type: 'object', value: 13, incr: [Function] }
{ type: 'object', value: 14, incr: [Function] }
{ type: 'object', value: 15, incr: [Function] }
guillaume@ubuntu:~/0x12$

Repo:

GitHub repository: alx-higher_level_programming
Directory: 0x12-javascript-warm_up
File: 103-object_fct.js

Files

README.md

Latest commit

History

README.md

File metadata and controls

Background Context

Resources

Read or watch:

Learning Objectives

General

Requirements

General

More Info

Install Node 14

Install semi-standard

Quiz questions

Question #0

Question #1

Question #2

Question #3

Question #4

Question #5

Tasks

0. First constant, first print

1. 3 languages

2. Arguments

3. Value of my argument

4. Create a sentence

5. An Integer

6. Loop to languages

7. I love C

8. Square

9. Add

10. Factorial

11. Second biggest!

12. Object

13. Add file

14. Const or not const

15. Call me Moby

16. Add me maybe

17. Increment object