hydrogen-web/scripts/build-plugins/service-worker.js

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const fs = require('fs/promises');
const path = require('path');
const xxhash = require('xxhashjs');
function contentHash(str) {
var hasher = new xxhash.h32(0);
hasher.update(str);
return hasher.digest();
}
function injectServiceWorker(swFile, otherUnhashedFiles, placeholdersPerChunk) {
const swName = path.basename(swFile);
let root;
let version;
let logger;
return {
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name: "hydrogen:injectServiceWorker",
apply: "build",
enforce: "post",
buildStart() {
this.emitFile({
type: "chunk",
fileName: swName,
id: swFile,
});
},
configResolved: config => {
root = config.root;
version = JSON.parse(config.define.DEFINE_VERSION); // unquote
logger = config.logger;
},
generateBundle: async function(options, bundle) {
const unhashedFilenames = [swName].concat(otherUnhashedFiles);
const unhashedFileContentMap = unhashedFilenames.reduce((map, fileName) => {
const chunkOrAsset = bundle[fileName];
if (!chunkOrAsset) {
throw new Error("could not get content for uncached asset or chunk " + fileName);
}
map[fileName] = chunkOrAsset.source || chunkOrAsset.code;
return map;
}, {});
const assets = Object.values(bundle);
const hashedFileNames = assets.map(o => o.fileName).filter(fileName => !unhashedFileContentMap[fileName]);
const globalHash = getBuildHash(hashedFileNames, unhashedFileContentMap);
const placeholderValues = {
DEFINE_GLOBAL_HASH: `"${globalHash}"`,
...getCacheFileNamePlaceholderValues(swName, unhashedFilenames, assets, placeholdersPerChunk)
};
replacePlaceholdersInChunks(assets, placeholdersPerChunk, placeholderValues);
logger.info(`\nBuilt ${version} (${globalHash})`);
}
};
}
function getBuildHash(hashedFileNames, unhashedFileContentMap) {
const unhashedHashes = Object.entries(unhashedFileContentMap).map(([fileName, content]) => {
return `${fileName}-${contentHash(Buffer.from(content))}`;
});
const globalHashAssets = hashedFileNames.concat(unhashedHashes);
globalHashAssets.sort();
return contentHash(globalHashAssets.join(",")).toString();
}
const NON_PRECACHED_JS = [
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"hydrogen-legacy",
"olm_legacy.js",
// most environments don't need the worker
"main.js"
];
function isPreCached(asset) {
const {name, fileName} = asset;
return name.endsWith(".svg") ||
name.endsWith(".png") ||
name.endsWith(".css") ||
name.endsWith(".wasm") ||
name.endsWith(".html") ||
// the index and vendor chunks don't have an extension in `name`, so check extension on `fileName`
fileName.endsWith(".js") && !NON_PRECACHED_JS.includes(path.basename(name));
}
function getCacheFileNamePlaceholderValues(swName, unhashedFilenames, assets) {
const unhashedPreCachedAssets = [];
const hashedPreCachedAssets = [];
const hashedCachedOnRequestAssets = [];
for (const asset of assets) {
const {name, fileName} = asset;
// the service worker should not be cached at all,
// it's how updates happen
if (fileName === swName) {
continue;
} else if (unhashedFilenames.includes(fileName)) {
unhashedPreCachedAssets.push(fileName);
} else if (isPreCached(asset)) {
hashedPreCachedAssets.push(fileName);
} else {
hashedCachedOnRequestAssets.push(fileName);
}
}
return {
DEFINE_UNHASHED_PRECACHED_ASSETS: JSON.stringify(unhashedPreCachedAssets),
DEFINE_HASHED_PRECACHED_ASSETS: JSON.stringify(hashedPreCachedAssets),
DEFINE_HASHED_CACHED_ON_REQUEST_ASSETS: JSON.stringify(hashedCachedOnRequestAssets)
}
}
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function replacePlaceholdersInChunks(assets, placeholdersPerChunk, placeholderValues) {
for (const [name, placeholderMap] of Object.entries(placeholdersPerChunk)) {
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const chunk = assets.find(a => a.type === "chunk" && a.name === name);
if (!chunk) {
throw new Error(`could not find chunk ${name} to replace placeholders`);
}
for (const [placeholderName, placeholderLiteral] of Object.entries(placeholderMap)) {
const replacedValue = placeholderValues[placeholderName];
const oldCode = chunk.code;
chunk.code = chunk.code.replaceAll(placeholderLiteral, replacedValue);
if (chunk.code === oldCode) {
throw new Error(`Could not replace ${placeholderName} in ${name}, looking for literal ${placeholderLiteral}:\n${chunk.code}`);
}
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}
}
}
/** creates a value to be include in the `define` build settings,
* but can be replace at the end of the build in certain chunks.
* We need this for injecting the global build hash and the final
* filenames in the service worker and index chunk.
* These values are only known in the generateBundle step, so we
* replace them by unique strings wrapped in a prompt call so no
* transformation will touch them (minifying, ...) and we can do a
* string replacement still at the end of the build. */
function definePlaceholderValue(mode, name, devValue) {
if (mode === "production") {
// note that `prompt(...)` will never be in the final output, it's replaced by the final value
// once we know at the end of the build what it is and just used as a temporary value during the build
// as something that will not be transformed.
// I first considered Symbol but it's not inconceivable that babel would transform this.
return `prompt(${JSON.stringify(name)})`;
} else {
return JSON.stringify(devValue);
}
}
function createPlaceholderValues(mode) {
return {
DEFINE_GLOBAL_HASH: definePlaceholderValue(mode, "DEFINE_GLOBAL_HASH", null),
DEFINE_UNHASHED_PRECACHED_ASSETS: definePlaceholderValue(mode, "UNHASHED_PRECACHED_ASSETS", []),
DEFINE_HASHED_PRECACHED_ASSETS: definePlaceholderValue(mode, "HASHED_PRECACHED_ASSETS", []),
DEFINE_HASHED_CACHED_ON_REQUEST_ASSETS: definePlaceholderValue(mode, "HASHED_CACHED_ON_REQUEST_ASSETS", []),
};
}
module.exports = {injectServiceWorker, createPlaceholderValues};