#JavaScript30 – Day 04

Day 4 consisted of what Wes called JavaScript cardio – exercises in JS.

The focus on this video was arrays and 4 array functions:


filter() will create a new array with all of the elements from another array that pass a test from a function.


The map() method takes in an array, performs a functions for each element in the array, then returns a new array of the same length.


Using sort() will sort the elements of an array inside of the array. It will take 2 items at a time, determines if one is a higher value, then will place them at a higher or lower index respectively.


reduce() performs a function against each value in the array and an”accumulator” (like a running total), then reduces it to a single value.


They’re all functions that I have seen in solutions for JS exercises in places like Free Code Camp  and HackerRank, but never really understood how or why they are used. And, even though I can tell you what they do, I could still use some work getting more comfortable actually working with these methods. Now that I’ve done this exercise once while just following along, I plan on going back to exercises like these to attempt to solve them on my own. I also have ideas on how to solve at least one of the FreeCodeCamp algorithm scripting challenges I’ve been stuck on.


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