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Add support for scraping CSS-in-JS based styles 👩‍🎤 #9

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Merged
merged 3 commits into from
Jul 4, 2019
Merged

Add support for scraping CSS-in-JS based styles 👩‍🎤 #9

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a1d1113
Add support for scraping CSS-in-JS based styles
bartveneman Jul 4, 2019
0c1d479
rm nyc output
bartveneman Jul 4, 2019
0359379
use package-lock.json
bartveneman Jul 4, 2019
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1 change: 0 additions & 1 deletion .gitignore
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@@ -1,2 +1 @@
node_modules
package-lock.json
6,954 changes: 6,954 additions & 0 deletions package-lock.json
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25 changes: 13 additions & 12 deletions src/index.js
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Expand Up @@ -48,17 +48,18 @@ module.exports = async (
// but not all...
const coverage = await page.coverage.stopCSSCoverage()

// Fetch all <style> tags from the page, because the coverage
// API may have missed some JS-generated <style> tags.
// Some of them *were* already caught by the coverage API,
// but they will be removed later on to prevent duplicates.
const styleTagsCss = (await page.$$eval('style', styles => {
// Get the text inside each <style> tag and trim() the
// results to prevent all the inside-html indentation
// clogging up the results and making it look
// bigger than it actually is
return styles.map(style => style.innerHTML.trim())
})).join('')
// Get all CSS generated with the CSSStyleSheet API
// See: https://developer.mozilla.org/en-US/docs/Web/API/CSSRule/cssText
const styleSheetsApiCss = await page.evaluate(() => {
/* global document */
return [...document.styleSheets]
.map(stylesheet =>
[...stylesheet.cssRules]
.map(cssStyleRule => cssStyleRule.cssText)
.join('')
)
.join('')
})

await browser.close()

Expand All @@ -73,5 +74,5 @@ module.exports = async (
.map(({text}) => text)
.join('')

return Promise.resolve(coverageCss + styleTagsCss)
return Promise.resolve(styleSheetsApiCss + coverageCss)
}
53 changes: 39 additions & 14 deletions test/index.js
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Expand Up @@ -8,13 +8,13 @@ const puppeteerCore = require('puppeteer-core')
const extractCss = require('..')

let server
const expected = readFileSync(resolve(__dirname, 'fixture.css'), 'utf8')
const fixture = readFileSync(resolve(__dirname, 'fixture.css'), 'utf8')

test.before(async () => {
server = await createTestServer()

server.get('/fixture.css', (req, res) => {
res.send(expected)
res.send(fixture)
})
})

Expand All @@ -27,11 +27,16 @@ test('it fetches css from a page with CSS in a server generated <link> inside th
server.get(url, (req, res) => {
res.send(`
<!doctype html>
<link rel="stylesheet" href="fixture.css" />
<html>
<head>
<link rel="stylesheet" href="fixture.css" />
</head>
</html>
`)
})

const actual = await extractCss(server.url + url)
const expected = fixture

t.is(actual, expected)
})
Expand All @@ -41,13 +46,14 @@ test('it fetches css from a page with CSS in server generated <style> inside the
server.get(url, (req, res) => {
res.send(`
<!doctype html>
<style>${expected.trim()}</style>
<style>${fixture}</style>
`)
})

const actual = await extractCss(server.url + url)
const expected = 'body { color: teal; }'

t.is(actual, expected.trim())
t.is(actual, expected)
})

test('it finds JS generated <link /> CSS', async t => {
Expand All @@ -62,6 +68,7 @@ test('it finds JS generated <link /> CSS', async t => {
})

const actual = await extractCss(server.url + path)
const expected = fixture

t.is(actual, expected)
})
Expand All @@ -77,7 +84,26 @@ test('it finds JS generated <style /> CSS', async t => {
})

const actual = await extractCss(server.url + url, {waitUntil: 'load'})
const expected = `body { color: teal; }`
const expected = 'body { color: teal; }'

t.is(actual, expected)
})

test('it finds css-in-js, like Styled Components', async t => {
const url = '/css-in-js'
const cssInJsExampleHtml = readFileSync(
resolve(__dirname, 'css-in-js.html'),
'utf8'
)
server.get(url, (req, res) => {
res.send(cssInJsExampleHtml)
})

const actual = await extractCss(server.url + url, {waitUntil: 'load'})
// Color is RGB instead of Hex, because of serialization:
// https://www.w3.org/TR/cssom-1/#serializing-css-values
const expected =
'html { color: rgb(255, 0, 0); }.hJHBhT { color: blue; font-family: sans-serif; font-size: 3em; }'

t.is(actual, expected)
})
Expand All @@ -94,9 +120,11 @@ test('it combines server generated <link> and <style> tags with client side crea

const actual = await extractCss(server.url + path)

t.true(actual.includes('content: "js-style";'))
t.true(actual.includes('content: "server-style";'))
t.true(actual.includes(`body {`))
t.true(actual.includes(`color: teal;`))
t.snapshot(actual)
t.true(actual.includes('counter-increment: 2;'))
t.true(actual.includes('counter-increment: 3;'))
})

test('it rejects if the url has an HTTP error status', async t => {
Expand All @@ -116,20 +144,17 @@ test('it accepts a browser override for usage with other browsers', async t => {
res.send(`
<!doctype html>
<style>
body::before {
content: ${req.headers['user-agent']};
}
body::before { content: "${req.headers['user-agent']}"; }
</style>
`)
})
const customBrowser = await puppeteerCore.launch({
executablePath: chromium.path,
args: ["--user-agent='Extract CSS Core'"]
args: ['--user-agent=Extract CSS Core']
})
const actual = await extractCss(server.url + path, {customBrowser})

t.snapshot(actual)
t.true(actual.includes("content: 'Extract CSS Core';"))
t.is(actual, 'body::before { content: "Extract CSS Core"; }')
})

test('it rejects on an invalid customBrowser option', async t => {
Expand Down
7 changes: 4 additions & 3 deletions test/kitchen-sink.html
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Expand Up @@ -9,17 +9,18 @@

<!-- Server generated style -->
<style>
.server-style {
counter-increment: 2;
.server-style::after {
content: 'server-style';
}
</style>

<h1>Title</h1>
<div class="server-style">server-style:</div>

<script>
// Client generated style
var style = document.createElement('style')
style.textContent = '.js-style { counter-increment: 3; }'
style.textContent = '.js-style::after { content: "js-style"; }'
document.body.appendChild(style)

// Client generated link
Expand Down
14 changes: 2 additions & 12 deletions test/snapshots/index.js.md
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Expand Up @@ -4,24 +4,14 @@ The actual snapshot is saved in `index.js.snap`.

Generated by [AVA](https://ava.li).

## it accepts a browser override for usage with other browsers

> Snapshot 1

`body::before {␊
content: 'Extract CSS Core';␊
}`

## it combines server generated <link> and <style> tags with client side created <link> and <style> tags

> Snapshot 1

`body {␊
`.server-style::after { content: "server-style"; }.js-style::after { content: "js-style"; }body {␊
color: teal;␊
}␊
body {␊
color: teal;␊
}␊
.server-style {␊
counter-increment: 2;␊
}.js-style { counter-increment: 3; }`
`
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