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A case study of Client Side Rendering
Wow, this has to be one of the best write ups of how to optimize your Webpack config that I’ve seen. Great dive into React page routing optimization as well.
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Great sunset clouds by Mt Hood
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The readability of bash always makes me think about how it was made by people who used to be legitimately concerned that more characters used in code actually made a program slower.
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When to reach for different JS methods while manipulating data
Array -> Array; structure different, length same
Reach for
.map
Array -> Array; structure same, length different
Reach for
.filter
Array -> Non-Array (like Object)
Reach for
.reduce
- easily one of the most powerful and flexible Array methods.Object -> Object; structure different, length same
The “entries” are super helpful, given an object like this:
const data = { firstName: 'Evan', lastName: 'Lovely', }
The “entries” (what you get if ran
Object.entries(data)
) would be:[ ['firstName', 'Evan'], ['lastName', 'Lovely'], ]
Being able to go to with
Object.entries
and from withObject.fromEntries
is very powerful and you then can use all the Array methods to do manipulations - so in the case of structure different, length same you’d reach for.map
:Object.fromEntries( Object.entries(myObject).map(([key, value]) => { // manipulate return [key, value]; }), );
Array -> Array; different structure, different length
It’s common to chain
.filter
and.map
together which works great if you are wanting a smaller number of items than you started with, but if you want to have the list grow - you’ll need to reach for something more powerful:.flatMap
.The common use of
.flatMap
is to use.map
and then if you end up with an array of arrays to.flat
them - however it can be much more powerful than that, from the MDN docs page:For adding and removing items during a map()
flatMap
can be used as a way to add and remove items (modify the number of items) during amap
. In other words, it allows you to map many items to many items (by handling each input item separately), rather than always one-to-one. In this sense, it works like the opposite offilter
. Return a 1-element array to keep the item, a multiple-element array to add items, or a 0-element array to remove the item.