Set property directly, rather than using defineProperty

[ironsidevsquincy]

Causing a big performance hit, e.g. every time this.body was being called, the function was run.

Starting with just this, but all the properties in here should set this directly

Using Engels as a test,

Before

$ siege -c 12 -t 20s http://localhost:3002/uk
...
Transactions:                 40 hits
Availability:             100.00 %
Elapsed time:              19.40 secs
Data transferred:          12.02 MB
Response time:              4.67 secs
Transaction rate:           2.06 trans/sec
Throughput:             0.62 MB/sec
Concurrency:                9.62
Successful transactions:          40
Failed transactions:               0
Longest transaction:            6.59
Shortest transaction:           1.73

After

$ siege -c 12 -t 20s http://localhost:3002/uk
...
Transactions:                 91 hits
Availability:             100.00 %
Elapsed time:              19.48 secs
Data transferred:          27.36 MB
Response time:              2.01 secs
Transaction rate:           4.67 trans/sec
Throughput:             1.40 MB/sec
Concurrency:                9.39
Successful transactions:          91
Failed transactions:               0
Longest transaction:            2.80
Shortest transaction:           1.21

[matthew-andrews]

wow, great work. i never liked defineProperty. too magic.

[wheresrhys]

I think defineProperty is still useful for expensive actions that don't need to be carried out for most instances, but the vast majority of the properties here don't meet this criteria

[i-like-robots]

I use defineProperty a few times in the related tags API for creating objects with dynamic key names, worth testing for speed?

https://github.com/Financial-Times/next-ft-api-client/blob/master/src/related-tags.js#L30-40

[phamann]

Nice!

[ironsidevsquincy]

It's not defineProperty that's inherently slow, it's just every time a property is called it runs the function, only to return a constant value in our case.

Particular example is this.readingTime was being called, which in turn was calling this.wordCount, which in turn was calling this.body, which was running the intensive dom.removeNonArticleLinks(dom.fixRelativeLinks(dom.removeEmptyParagraphs(html))) every time, even though these values don't change. And when you've got this, which was calling readingTime up to 3 times, you get a major slowdown

Basically, only use defineProperty if you need to watch the setting/getting of a property, of the property changes