# For excercises

## TIK TOK CHINA exercise.

Create a JS program that gets a number from the user and then print the numbers from 0 to the number provided by the user and do the following calcuations.

1- if the number is divisible by 3 it should print TIK instead of the number.

2- If the number is divisible by 5 it should print TOK instead of the number.

3- If the number is divisible by 3 and 5 it should print CHINA instead of the number.

4- Use prompt to get the value from the user.

5- Use console.log to print the output to the console.

Examples of when user inputs 20

``````1
2
TIK
4
TOK
TIK
7
8
TIK
TOK
11
TIK
13
14
CHINA
16
17
TIK
19
TOK
``````

## 2 cristmas tree

Write a program that receives a value from a user using prompt and draw a christmas tree using * and spaces with the same level of lines as the number inserted by the user.

Example when user inputs 5

``````    *
***
*****
*******
*********``````

## 3 Enigma machine

Create a program that can encrypt messages using the following rules

1-The program should ask if it needs to encrypt or decrypt

2- the program will receive a phrase in english in lower case

3. the program should replace the letters as follows table, (depending if is encrypting or decrypting.

4 any other character should remain unchanged.

example, if the program receives the string “cat” it should return “vke“. when encrypting

In the same way, if the program gets the string ‘vke’, it should return ‘cat’ if decrypting

NOTES:

if you have a variable string

var str = “hello”

you can get characters at specific part of the string with

str.charAt(2)

you can get the length of the string with

str.length

## 4 Roman Nightmare

Make a program that translates a number provided by the user between 1 and 399 and translates it to roman numbers.

Example when inserting 7 output should be VII

Example when inserting 399 output should be CCCXCIX

Example when inserting 159 output should be CLIX

Notes:, in roman numbers the following equivalences hold true

I = 1

V = 5

X = 10

L = 50

C = 100

III = 3

XXX = 30

III = 300

# for loop basics

A for loop allows to execute a piece of code several times.

Example 1.0

``````for(var i =0; i<10; i++)
{
console.log("I am printing this message 10 times");
}``````

If the previous code where to run in chrome we could see the following output in the console.

Basic structure of for loop

``````for(    INITIALIZATION     ;     CONDITION     ;    INCREMENT    )
{
CODE
}``````

We have 4 main parts that build the for

• INITIALIZATION: Executed only one time at all.
• CONDITION: Executed before the code is executed. (executed several times)
• CODE: Executed only if CONDITION is meet (executed several times)
• INCREMENT: Executed after the code is executed. (executed several times)

The following diagram shows how the flow of a for is performed.

so in our original example 1.0 we could spread the parts of the for as follows.

``````for(var i =0; i<10; i++)
{
console.log("I am printing this message 10 times");
}``````

## NOTE THAT

• INITIALIZATION executes only once.
• the CONDITION will be executed as long as it is meet.
• Every time the CONDITION is meet, the CODE and the INCREMENT will execute once.

# JS Variable Basics

Variables are used to store values in js.

Examples

``````var a = 1;
//the previous variable holds a number.
var b = "hello, how are you"
//the previous variable holds a string.``````