Modern JavaScript from the Beginning - Second Edition - Array.filter Method

The video tutorial covers high order array methods in JavaScript, focusing on the filter method. It explains the differences between forEach and filter, demonstrating how filter can be used to return modified arrays based on conditions. The tutorial includes examples of filtering even numbers and more complex object filtering. It concludes with a brief introduction to the map method, which will be covered in the next video.

What is a key difference between 'forEach' and 'filter'?

• 'forEach' modifies the original array.

• 'filter' returns a new array based on a condition.

• 'forEach' is used for mathematical operations.

• 'filter' does not return any value.

In the example with words, what is the purpose of the arrow function?

• To modify the original array.

• To test each word's length.

• To sort the words alphabetically.

• To convert words to uppercase.

How can you filter even numbers from an array using 'filter'?

• By checking if the number is greater than 5.

• By using a 'forEach' loop.

• By converting numbers to strings.

• By using the modulus operator to check divisibility by 2.

What is a disadvantage of using 'forEach' compared to 'filter'?

• 'forEach' is faster than 'filter'.

• 'forEach' requires more lines of code to achieve the same result.

• 'forEach' can only be used with strings.

• 'forEach' automatically sorts the array.

When filtering company objects, what condition is used to find retail companies?

• Checking if the company has more than 100 employees.

• Checking if the company name starts with 'R'.

• Checking if the company is based in a specific location.

• Checking if the company category is 'retail'.

How do you filter companies that started after 1980 and ended before 2005?

• By using conditions on both start and end dates.

• By checking if the end date is greater than 2005.

• By filtering based on company revenue.

• By checking if the start date is less than 1980.

What condition is used to filter companies that lasted 10 years or more?

• Checking if the company has more than 10 employees.

• Checking if the company name has more than 10 characters.

• Checking if the difference between end and start dates is 10 or more.

• Checking if the company is in the technology sector.

Why is the 'filter' method useful in user interfaces?

• It automatically updates the database.

• It allows for dynamic filtering based on user input.

• It helps in sorting data alphabetically.

• It is used for styling elements.

What will be discussed in the next video after 'filter'?

• The 'reduce' method.

• The 'sort' method.

• The 'map' method.

• The 'splice' method.

What is the main advantage of using 'filter' over 'forEach'?

• 'filter' returns a new array based on a condition.

• 'filter' can modify the original array.

• 'filter' is easier to read and write.

• 'filter' is faster in execution.