Section 6: Async Foundations

Question 1

Define a “Callback Function”

Answer 1

A function that is passed into another function as a parameter, then invoked by that other function.

Question 2

Name the parameters of the ‘forEach’ method

Answer 2

forEach(array, callback)

someArray.forEach(function(element, index, array) {
console.log(item);
});

Question 3

Name the parameters of the callback function inside the forEach method.

Answer 3

someArray.forEach(function(element, index, array) {
console.log(element);
});

Question 4

What does the the ‘findIndex’ method do?

Answer 4

It returns the index of the first element in the array for which the callback returns a truthy value. ‘-1’ is returned if the callback never returns a truthy value.

Question 5

Define how ‘the Stack’ is set up and how it works.

Answer 5

• An ordered set of stack frames
• Most recently invoked function is on the top of the stack
• The bottom of the stack is the first function invoked
• The stack is processed from top to bottom.

Question 6

Define ‘the Heap’

Answer 6

• An area in memory where your data is stored