 # Loops practice in JavaScript

Use a loop to output a column of numbers from `1` to `100`.

Use a loop to output a column of numbers from `100` to `1`.

Use a loop to output a column of even numbers from `1` to `100`.

Fill the array with `10` x using a loop.

Fill the array with numbers from `1` to `10` using a loop.

Given an array of numbers. Using the loop, output only those elements of the array that are greater than zero and less than `10`.

Given an array of numbers. Use a loop to check that it has an element with value `5`.

Given an array of numbers. Use a loop to find the sum of the elements of this array.

Given an array of numbers. Use a loop to find the sum of the squares of the array elements.

Given an array of numbers. Find the arithmetic mean of its elements.

Write a script that will find the factorial of a number. Factorial is the product of all integers from one to a given number.

Fill the array with numbers from `10` to `1` using a loop.

Given an array of numbers. Numbers can be positive or negative. Find the sum of positive array elements.

Given an array of numbers, for example:

`let arr = [10, 20, 30, 50, 235, 3000];`

Print only those numbers from the array that start with `1`, `2` or `5`.

Given an array of numbers. Print the elements of this array in reverse order.

Given an array of numbers. Use a loop to display all elements whose value matches their index number in the array.

Given an array of numbers. Using the loop `for` and the function `document.write` print each element of the array in a new line. Use the `br` tag for this.

Given an array of numbers. Using the loop `for` and the function `document.write` print each element of the array in a separate paragraph.

Make an array of days of the week. Use the loop `for` to output all the days of the week, and output the weekends in bold.

Make an array of `days of the week`. Use the loop `for` to print all the days of the week, and print the current day in italics. The number of the current day should be stored in the variable `day`.

Given the following object with employees and their salaries:

```let obj = { employee1: 100, employee2: 200, employee3: 300, employee4: 400, employee5: 500, employee6: 600, employee7: 700, };```

Increase the salary of each employee by `10%`.

Modify the previous task so that the salary increases only for those employees whose salary is less than or equal to `400`.

Given the following arrays:

```let arr1 = [1, 2, 3, 4, 5]; let arr2 = [6, 7, 8, 9, 10];```

Using these arrays, create a new object, making its keys from the elements of the first array and its values from the elements of the second.

Given the following object:

`let obj = {1: 6, 2: 7, 3: 8, 4: 9, 5: 10};`

Find the sum of the object keys and divide it by the sum of the object values.

Given the following object:

`let obj = {'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5};`

Write the object keys to one array and the values to another.

Given the following object:

```let obj = { 1: 125, 2: 225, 3: 128, 4: 356, 5: 145, 6: 281, 7: 452, };```

Write to the new array the elements whose value starts with the number `1` or the number `2`. That is, you will end up with an array like this:

```let arr = [ 125, 225, 128, 145, 281, ];```

Given the following array:

`let arr = ['a', 'b', 'c', 'd', 'e'];`

Create the following object from this array:

`let arr = {1: 'a', 2: 'b', 3: 'c', 4: 'd', 5: 'e'};`

Given the following array:

`let arr = ['a', 'b', 'c', 'd', 'e'];`

Create the following object from this array:

`let arr = {'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5};`