5.8 Extra Practice¶

Let Usage¶

Task 1: Display the even numbers from 0 to 20.

for(var i = 0; i <= 20; i = i + 2){
  console.log(i);
}

The result is as follows:

0
2
4
.
.
.
20

Task 2: Check the following code.

var i = 5;

for(var i = 0; i <= 20; i = i + 2){
  console.log(i);
}
console.log("..........");
console.log(i);

The result is as follows:

0
2
4
.
.
.
20
..........
22

Task 3: Check the following code.

var i = 5;

for(let i = 0; i <= 20; i = i + 2){
  console.log(i);
}
console.log("..........");
console.log(i);

The result is as follows:

0
2
4
.
.
.
20
..........
5

Task 4: Display the elements of the following array.

var users = ["user1", "user2", "user3", "user4"];

for(var user of users){
  console.log(user);
}

The result is as follows:

user1
user2
user3
user4

Task 5: Check the following the code.

var users = ["user1", "user2", "user3", "user4"];
var user = "Sanad";

for(var user of users){
  console.log(user);
}

console.log("...........");
console.log(user);

The result is as follows:

user1
user2
user3
user4
...........
user4

Task 6: Check the following the code.

var users = ["user1", "user2", "user3", "user4"];
var user = "Sanad";

for(let user of users){
  console.log(user);
}

console.log("...........");
console.log(user);

The result is as follows:

user1
user2
user3
user4
...........
Sanad

Task 7: Display the properties of the following object.

var myObj = {
  a: 1,
  b: 2,
  c: 3
}

for(var prop in myObj){
  console.log(prop);
}

The result is as follows:

a
b
c

Task 8: Check the following code.

var myObj = {
  a: 1,
  b: 2,
  c: 3
}

var prop = "d";

for(var prop in myObj){
  console.log(prop);
}

console.log(".........");
console.log(prop);

The result is as follows:

a
b
c
.........
c

Task 9: Check the following code.

var myObj = {
  a: 1,
  b: 2,
  c: 3
}

var prop = "d";

for(let prop in myObj){
  console.log(prop);
}

console.log(".........");
console.log(prop);

The result is as follows:

a
b
c
.........
d

Task 10: Check the following code.

var user = "Jad";
var id = 77;

if(user === "Jad"){
  var id = 54;
}else{
  var id = 44;
}

console.log(id);

The result is: 54

Task 11: Check the following code.

var user = "Jad";
var id = 77;

if(user === "Jad"){
  let id = 54;
}else{
  let id = 44;
}

console.log(id);

The result is: 77

Const Usage¶

Task 12: Calculate the result of e ** t + 1 for t=0? The value of e constant is 2.7.

const E = 2.7;

console.log(E ** 0 + 1);

The result is: 2

Task 13: Generate 4 users' IDs starting from 45.

const IDSTART = 45;

for (let i = idStart; i < idStart + 4; i++){
  console.log(i)
}

The result is as follows:

45
46
47
48

Task 14: What is the circumference of a circle with diameter 2cm?

const PI = 3.14;

console.log(2 * PI * 1);

The result is: 6.28

Task 15: Check the following code.

const ARR = ["user1", "user2", "user3"];

function searchForUser(user, usersArr){
  if(usersArr.indexOf(user) !== -1){
    console.log("Found in your array.");
  }else if(ARR.indexOf(user) !== -1){
    console.log("Found in the default array.")
  }else{
    console.log("Sorry, the user is not registered with us.")
  }
}

searchForUser("user5", ["user5", "user6", "user88"]);
searchForUser("user1", ["user5", "user6", "user88"]);
searchForUser("user200", ["user5", "user6", "user88"]);

The result is as follows:

Found in your array.
Found in the default array.
Sorry, the user is not registered with us.

Task 16: Refer to task 15; update the default array ARR, and add user899, user795, and user200.

const ARR = ["user1", "user2", "user3"];

function searchForUser(user, usersArr){
  if(usersArr.indexOf(user) !== -1){
    console.log("Found in your array.");
  }else if(ARR.indexOf(user) !== -1){
    console.log("Found in the default array.")
  }else{
    console.log("Sorry, the user is not registered with us.")
  }
}

searchForUser("user5", ["user5", "user6", "user88"]);
searchForUser("user1", ["user5", "user6", "user88"]);
searchForUser("user200", ["user5", "user6", "user88"]);

ARR.push("user899");
ARR.push("user795");
ARR.push("user200");

console.log("................");
searchForUser("user200", ["user5", "user6", "user88"]);

The result is as follows:

Found in your array.
Found in the default array.
Sorry, the user is not registered with us.
................
Found in the default array.