refactor(open_graph): drop cheerio and use regex

[SukkaW]

What does it do?

cheerio is slow and we only use that to parse and list img in post.content. This PR drop cheerio and use regex to do the job.

How to test

git clone -b BRANCH https://github.com/USER/hexo.git
cd hexo
npm install
npm test

Screenshots

913f5be

	NodeJS 8	NodeJS 10	NodeJS 12
cheerio@0.22 (hexojs/hexo#master)	7.12	6.96	6.86
regex (This PR)	7.15	6.96	6.78
dom-parser (#3679)	7.2	6.93	6.82
conditional cheerio (#3670)	7.15	6.92	6.78

4f86dde

	NodeJS 8	NodeJS 10	NodeJS 12
cheerio@0.22 (hexojs/hexo#master)	7.03	6.59	6.51
regex (This PR)	7.01	6.57	6.45
dom-parser (#3679)	6.98	6.56	6.41
conditional cheerio (#3670)	7.00	6.60	6.38

5c309eb

	NodeJS 8	NodeJS 10	NodeJS 12
cheerio@0.22 (hexojs/hexo#master)	6.96	6.65	6.85
regex (This PR)	6.90	6.68	6.73
dom-parser (#3679)	6.88	6.67	6.73
conditional cheerio (#3670)	6.72	6.60	6.80

c11ded4

	NodeJS 8	NodeJS 10	NodeJS 12
cheerio@0.22 (hexojs/hexo#master)	7.29	6.54	6.93
regex (This PR)	7.21	6.47	6.84
dom-parser (#3679)	7.16	6.50	6.87
conditional cheerio (#3670)	7.06	6.50	6.81

Pull request tasks

• Add test cases for the changes.
• Passed the CI test.

[coveralls]

Coverage increased (+0.0008%) to 97.155% when pulling 3e0b0dc on SukkaW:og-img-regex into 49c7d4a on hexojs:master.

[SukkaW]

For regex, I have test those pattern with regex101 to match this post:

/<img.*?src="(.*?)".*?\/?>/gi

6491 steps, 9 matches, ~3ms: https://regex101.com/r/N1Rv9w/1

/<img.*?(?:>|\/>)/gi

8858 steps, 9 matches, ~5ms: https://regex101.com/r/N1Rv9w/2

/<img(.*?)>/gi

6527 steps, 9 matches, ~4ms: https://regex101.com/r/N1Rv9w/3

/<img.*?>/gi

4313 steps, 9 matched, ~3ms: https://regex101.com/r/N1Rv9w/4

/<img[^>]*src[="'\s]+[^.]*\/([^.]+)\.[^"']+["']?[^>]*>/gi

4627 steps, 9 matched, ~4ms: https://regex101.com/r/N1Rv9w/5

Currently in this PR I am using the first one.

Update

After 4f86dde I am now using the forth one.

Update

/<img [^>]*src=['"]([^'"]+)([^>]*>)/gi

4573 steps, 9 matched, ~4ms: https://regex101.com/r/N1Rv9w/7

[SukkaW]

I think we still need to dig into those PR: #3679 #3670 and this PR. They all increase performance, but not much.

[segayuu]

LGTM!

[curbengh]

Since this PR only uses native API, naturally it supersedes #3679 #3670. This is unless there is possibility of some edge cases, which I currently don't foresee.

[SukkaW]

@segayuu @curbengh Should I add some test cases for <img> tags with empty src attribute?

[SukkaW]

I have update the final benchmark for this PR & #3670

	NodeJS 8	NodeJS 10	NodeJS 12
cheerio@0.22 (hexojs/hexo#master)	8.75	7.0	7.82
regex (This PR)	6.51	5.52	6.44
conditional cheerio (#3670)	7.68	6.49	7.51

The last benchmark shows this PR increase performance by nearly 20%.

I will merge this PR and close #3670 then.