Algorithm Book - Chapter 3 - Arrays

Question 1

What are array inspection functions?

Answer 1

min(arr), max(arr), sum(arr), avg(arr)

Question 2

What scenarios are arrays good for? not good for?

Answer 2

Arrays are good for random-access and to be read in a differen roder than they were added. Arrays are less suitable (still common) in scenarios with many insertsiona d removals.

Question 3

Arrays can be sparse? explain

Answer 3

You can push values at arr.length +1..the value at arr.length would be undefined.

Question 4

Describe passing by reference

Answer 4

Arrays are passed by reference. This means that a pointer is sent when an array is sent as an argument. Therefore, even though parameters are always copies of originals, with arrays (and all objects) a pointer is copied, resulting in caller and callee both having a copy of the same pointer. Hence both are looking at the same location in memory, and hence both will reference the same array. When you pass an array to a function, that array is “live”: changes the callee makes in that array will be reflected when we return to the caller, regardless of whether the called function returns that array.

Question 5

Javascript is loosely written

Answer 5

Because of it’s data types. JavaScript considers almost everything an object, since almost every possible values has a set of methods attached (valueOf, toString, etc.)

Question 6

What are the data types?

Answer 6

Boolean, Number, String, Object, Function, and undefined.

Question 7

Describe falsey and truthy

Answer 7

Six values are nothing: false, 0, NaN, “”, null, undefined

Truthy: objects, functions, non-0 numbers and non-empty strings