COMP3512

winter 2024

lec-js-02

The Next Stretch

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13th: Midterm 2 (JS)

15th: Withdraw Deadline

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ExecuteProgram's

JavaScript Arrays lessons

16 free lessons will get you through most of it - and lots of what we cover. Highly recommended.

let's talk about these things today:

◉ forEach()
◉ find()
◉ filter()
◉ sort()
◉ map()

5 Useful Array Methods

But first, let's talk about callbacks.

00-callbacks

In JS, functions are just "callable objects"! And like any object, you can use them as arguments in other functions.

What about arrow functions?

We'll get to them later in the course.

They're optional, but very common.

If you are keen to use them now, you have my blessing...and sympathies.

forEach()

forEach() is a "convenient" way to iterate through an array

01-forEach

find()

find() gets you the FIRST thing in an array that meets some criterion

02-find

filter()

filter() is just like find()...except now you get an array of 0 or more things back

03-filter

BRAIN BREAK

sort()

sort() works a lot like Collections.sort(), which you encountered in COMP2503

04-sort

map()

Think of map() as a magic wand that creates an array of things from an array of different things.

05-map

Warning: that analogy has some flaws....