56 lines
1.9 KiB
JavaScript
56 lines
1.9 KiB
JavaScript
import fs from 'fs'
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import { visit } from 'unist-util-visit'
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// Matches any <img> tags with an href that starts with `/assets/` or '/public/'
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const matcher = (node) =>
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node.type === 'element' &&
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node.tagName === 'img' &&
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node.properties &&
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node.properties.src &&
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(node.properties.src.startsWith('/assets/') || node.properties.src.startsWith('/public/'))
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// Content authors write images like ` {
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return (tree) => {
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visit(tree, matcher, (node) => {
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const newSrc = getNewSrc(node)
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if (newSrc) {
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node.properties.src = newSrc
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}
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})
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}
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}
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function getNewSrc(node) {
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const { src } = node.properties
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if (!src.startsWith('/')) return
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try {
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const filePath = src.slice(1)
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const stats = fs.statSync(filePath)
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// The size is not perfect but it's good enough. The size is
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// very fast to pick up without needing to do a deep hashing of the
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// image's content. It's perfectly possible that someone edits an
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// image and it's size doesn't change. Although very unlikely.
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// The slightest change to the image is more likely to either increase
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// or decrease the image size by at least 1 byte.
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// Also, because of this limitation, we're not confident to cache the
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// image more than say 24h. But in the unlikely event that someone does
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// edit an image and the size doesn't change, there's always the
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// escape hatch that you can soft-purge all manual CDN surrogate keys.
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if (!stats.size) return
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const hash = `${stats.size}`
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const split = src.split('/')
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split.splice(2, 0, `cb-${hash}`)
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return split.join('/')
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} catch (err) {
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console.warn(
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`Failed to get a hash for ${src} ` +
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'(This is mostly harmless and can happen with outdated translations).'
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)
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}
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}
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