FlatMap & Flatten - HTTP203 Advent

Key Takeaways

[Music] so 2017 pretty much dead to us it's all last year but the next one in a linear fashion 2018 very much interested about that so I've been thinking about some of the features of the web that going to be sort of landing on discussed around then and I wanted to see if I could describe one of them to you in two minutes and I think I'm going to describe to you is a flat map and flattened what good question these are methods that are going to go on a race oh this is like the I think the array protip hasn't been changed in a long long time so this would be the first new array prototype function along yeah it since we had things like some and finds find index yeah but what does flat map and like what flatten what is Latin okay frightened if you have an array of arrays it will go for it and just turn it into one long array as if each array is concatenate one your level will recurs down aha good question one of the arguments is depth which basically says how many times it will run you know give infinite infinity a step that is a good question of which I do not know the answer that is that is a fun thing to look up flood map map dope or just what I might do it's you know map I know map so you take you take an array and you apply function to every element yes and it will always produce an array the same length of yeah of the array you operate on it be a new array but you can like you know change every item for another item yeah I'd seen you change Dom nodes for Strings or whatever whereas reduce always takes you down to select one element is the idea taking away down to one element flatmap lets you look at an item and you return an array of items oh so it's like map and then flatten exactly hence the name map yes you've spotted the two words in there that join together to form what this does but it's something that I found that I've needed quite a bit yeah like I usually use reduced by like push to my accumulator value and it kind of feels like hockey z-9 right right exactly so it's a way to remove of the annoyance and you just get to you know create an array of arbitrary length from an array of arbitrary length by returning history or a games and that's stage free in TC 49 I'm looking forward to that we're getting good at this yeah async iterators and generators okay now I'm aware of iterators I am aware of generators exactly what you've done there is put the word async in front of them right okay the poppers anything we're done