Slim down by using a for/in loop

[kddnewton]

for/in returns the index for arrays, so this just works. Passes all the tests.

Before:

 122 B: dlv.js.gz
91 B: dlv.js.br
121 B: dlv.es.js.gz
97 B: dlv.es.js.br
198 B: dlv.umd.js.gz
160 B: dlv.umd.js.br

After:

 109 B: dlv.js.gz
83 B: dlv.js.br
110 B: dlv.es.js.gz
83 B: dlv.es.js.br
185 B: dlv.umd.js.gz
151 B: dlv.umd.js.br

[RReverser]

Really well done!

[lukeed]

So fun to do this 😆I had the same thing inside clsx originally, but ultimately reversed it for proper Array handling. Doing so (re)gained at least 2x performance: lukeed/clsx@91f5e68

I'm definitely all for cheeky golfing, but I think should maybe do a before/after comparison of this change.

[jonasraoni]

From:
module.exports=function(t,i,n,o,r){for(o in i=i.split?i.split("."):i)t=t?t[i[o]]:r;return t===r?n:t};
To:
module.exports=function(t,i,n,o,r){for(o in i=i.sub?i.split('.'):i)t=t?t[i[o]]:r;return t===r?n:t};

I was going to shave a bit more using template literals split`.` , but I see it's not in ES5 :L

Whatever, I think there should be a break in the loop.

[kddnewton]

The other solution I came up with was:

exportdefaultfunctiondlv(obj,key,def,p,undef){key=key.split ? key.split('.') : key;for(p=0;obj&&p<key.length;obj=obj[key[p++]]);returnp<key.length||obj===undef ? def : obj;}

which does bail out early for deeply nested objects. It depends on if you want the trimmest version possible or the most efficient. If you're going for efficiency then I can change over to this one. Stats for that:

 126 B: dlv.js.gz
92 B: dlv.js.br
126 B: dlv.es.js.gz
100 B: dlv.es.js.br
200 B: dlv.umd.js.gz
177 B: dlv.umd.js.br

It's a difference of 17 bytes, so up to you.

[RReverser]

Bailing out early is what dlv has been doing before my PR - #30 - but I changed it to reduce size and I still believe that early fallout is not common nor does it give any substantial win to justify a more complicated code.

[jonasraoni]

I agree! But this is an episode of "what has been seen cannot be unseen" :)
Whatever, micro improvements are normally pointless, but that's where the fun lives \o/

[RReverser]

@jonasraoni FWIW this one

module.exports=function(t,i,n,o,r){for(o in i=i.sub?i.split('.'):i)t=t?t[i[o]]:r;return t===r?n:t};

was pretty cool, but results in an actually larger size after compression (as shown by npm run build) due to two different words.

[luanmuniz]

Just a note. forin loops are a lot less performative then normal for loops.

I don't think this should aim for fewer bytes in the module rather than performance.

IMHO Even if we double the byte size, if we increase the performance I think it's still valid.

[RReverser]

I don't think this should aim for fewer bytes

That's precisely the goal of this helper library AFAIK. If someone cares about performance, they shouldn't use string-based dynamic paths in the first place, but when they do, microimprovements of loops are not going to change much.

[mikesherov]

If performance is not a goal, then array reduce gives a smaller implementation, as pointed out in a few existing PRs: #8

I got:

Build "dlv" to dist:
119 B: dlv.js.gz
83 B: dlv.js.br
118 B: dlv.es.js.gz
89 B: dlv.es.js.br
190 B: dlv.umd.js.gz
150 B: dlv.umd.js.br

with:

export default function dlv(obj, key, def, p, undef) {
key = key.split ? key.split('.') : key;
obj = key.reduce(function(obj, p) {
return obj ? obj[p] : undef
}, obj);
return obj === undef ? def : obj;
}

[lukeed]

Jason's libraries are typically a balance of code size and performance. That's why they're so great.

I don't want to speak for him, but losing 13 bytes for less than half the performance is generally not worth it.

Source: https://esbench.com/bench/5ce6e64a4cd7e6009ef62526

[mikesherov]

Here's the reduce version added to that bench as "Test 3":

https://esbench.com/bench/5ce6e64a4cd7e6009ef62526

[mikesherov]

Seems like reduce gives the size savings while only being 6% slower than for-in

[mikesherov]

Sorry, actually smaller!!!

Build "dlv" to dist:
117 B: dlv.js.gz
82 B: dlv.js.br
116 B: dlv.es.js.gz
81 B: dlv.es.js.br
188 B: dlv.umd.js.gz
148 B: dlv.umd.js.br

for:

export default function dlv(obj, key, def, undef) {
key = key.split ? key.split('.') : key;
obj = key.reduce(function(obj, p) {
return obj ? obj[p] : undef
}, obj);
return obj === undef ? def : obj;
}

[mikesherov]

I opened a PR for the reduce version: #36