internal/web_package/injector.js - third_party/github/bazel-contrib/rules_nodejs - Git at Google

 /**
  * @license
  * Copyright 2018 The Bazel Authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  *
  * You may obtain a copy of the License at
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 const parse5 = require('parse5');
 const treeAdapter = require('parse5/tree-adapters/default');
 const fs = require('fs');
 const path = require('path');

 function findElementByName(d, name) {
   if (treeAdapter.isTextNode(d)) return undefined;
   if (d.tagName && d.tagName.toLowerCase() === name) {
     return d;
   }
   if (!treeAdapter.getChildNodes(d)) {
     return undefined;
   }
   for (let i = 0; i < treeAdapter.getChildNodes(d).length; i++) {
     const f = treeAdapter.getChildNodes(d)[i];
     const result = findElementByName(f, name);
     if (result) return result;
   }
   return undefined;
 }

 function main(params, read = fs.readFileSync, write = fs.writeFileSync, timestamp = Date.now) {
   const outputFile = params.shift();
   const inputFile = params.shift();
   const rootDirs = [];
   while (params.length && params[0] !== '--assets') {
     let r = params.shift();
     if (!r.endsWith('/')) {
       r += '/';
     }
     rootDirs.push(r);
   }
   // Always trim the longest prefix
   rootDirs.sort((a, b) => b.length - a.length);
   params.shift(); // --assets

   const document = parse5.parse(read(inputFile, {encoding: 'utf-8'}), {treeAdapter});

   const body = findElementByName(document, 'body');
   if (!body) {
     throw ('No <body> tag found in HTML document');
   }

   const head = findElementByName(document, 'head');
   if (!head) {
     throw ('No <head> tag found in HTML document');
   }

   /**
    * Trims the longest prefix from the path
    */
   function relative(execPath) {
     for (const r of rootDirs) {
       if (execPath.startsWith('external/')) {
         execPath = execPath.substring('external/'.length);
       }
       if (execPath.startsWith(r)) {
         return execPath.substring(r.length);
       }
     }
     return execPath;
   }

   const jsFiles = params.filter(s => /\.m?js$/i.test(s));
   for (const s of jsFiles) {
     // Differential loading: for filenames like
     //  foo.mjs
     //  bar.es2015.js
     // we use a <script type="module" tag so these are only run in browsers that have ES2015 module
     // loading
     if (/\.(es2015\.|m)js$/i.test(s)) {
       const moduleScript = treeAdapter.createElement('script', undefined, [
         {name: 'type', value: 'module'},
         {name: 'src', value: `/${relative(s)}?v=${timestamp()}`},
       ]);
       treeAdapter.appendChild(body, moduleScript);
     } else {
       // Other filenames we assume are for non-ESModule browsers, so if the file has a matching
       // ESModule script we add a 'nomodule' attribute
       function hasMatchingModule(file, files) {
         const noExt = file.substring(0, file.length - 3);
         const testMjs = (noExt + '.mjs').toLowerCase();
         const testEs2015 = (noExt + '.es2015.js').toLowerCase();
         const matches = files.filter(t => {
           const lc = t.toLowerCase();
           return lc === testMjs || lc === testEs2015;
         });
         return matches.length > 0;
       }

       // Note: empty string value is equivalent to a bare attribute, according to
       // https://github.com/inikulin/parse5/issues/1
       const nomodule = hasMatchingModule(s, jsFiles) ? [{name: 'nomodule', value: ''}] : [];

       const noModuleScript = treeAdapter.createElement('script', undefined, nomodule.concat([
         {name: 'src', value: `/${relative(s)}?v=${timestamp()}`},
       ]));
       treeAdapter.appendChild(body, noModuleScript);
     }
   }

   for (const s of params.filter(s => /\.css$/.test(s))) {
     const stylesheet = treeAdapter.createElement('link', undefined, [
       {name: 'rel', value: 'stylesheet'},
       {name: 'href', value: `/${relative(s)}?v=${timestamp()}`},
     ]);
     treeAdapter.appendChild(head, stylesheet);
   }

   const content = parse5.serialize(document, {treeAdapter});
   write(outputFile, content, {encoding: 'utf-8'});
   return 0;
 }

 module.exports = {main};

 if (require.main === module) {
   // We always require the arguments are encoded into a flagfile
   // so that we don't exhaust the command-line limit.
   const params = fs.readFileSync(process.argv[2], {encoding: 'utf-8'}).split('\n').filter(l => !!l);
   process.exitCode = main(params);
 }
	/**
	* @license
	* Copyright 2018 The Bazel Authors. All rights reserved.
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	*
	* You may obtain a copy of the License at
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	const parse5 = require('parse5');
	const treeAdapter = require('parse5/tree-adapters/default');
	const fs = require('fs');
	const path = require('path');

	function findElementByName(d, name) {
	if (treeAdapter.isTextNode(d)) return undefined;
	if (d.tagName && d.tagName.toLowerCase() === name) {
	return d;
	}
	if (!treeAdapter.getChildNodes(d)) {
	return undefined;
	}
	for (let i = 0; i < treeAdapter.getChildNodes(d).length; i++) {
	const f = treeAdapter.getChildNodes(d)[i];
	const result = findElementByName(f, name);
	if (result) return result;
	}
	return undefined;
	}

	function main(params, read = fs.readFileSync, write = fs.writeFileSync, timestamp = Date.now) {
	const outputFile = params.shift();
	const inputFile = params.shift();
	const rootDirs = [];
	while (params.length && params[0] !== '--assets') {
	let r = params.shift();
	if (!r.endsWith('/')) {
	r += '/';
	}
	rootDirs.push(r);
	}
	// Always trim the longest prefix
	rootDirs.sort((a, b) => b.length - a.length);
	params.shift(); // --assets

	const document = parse5.parse(read(inputFile, {encoding: 'utf-8'}), {treeAdapter});

	const body = findElementByName(document, 'body');
	if (!body) {
	throw ('No <body> tag found in HTML document');
	}

	const head = findElementByName(document, 'head');
	if (!head) {
	throw ('No <head> tag found in HTML document');
	}

	/**
	* Trims the longest prefix from the path
	*/
	function relative(execPath) {
	for (const r of rootDirs) {
	if (execPath.startsWith('external/')) {
	execPath = execPath.substring('external/'.length);
	}
	if (execPath.startsWith(r)) {
	return execPath.substring(r.length);
	}
	}
	return execPath;
	}

	const jsFiles = params.filter(s => /\.m?js$/i.test(s));
	for (const s of jsFiles) {
	// Differential loading: for filenames like
	// foo.mjs
	// bar.es2015.js
	// we use a <script type="module" tag so these are only run in browsers that have ES2015 module
	// loading
	if (/\.(es2015\.\|m)js$/i.test(s)) {
	const moduleScript = treeAdapter.createElement('script', undefined, [
	{name: 'type', value: 'module'},
	{name: 'src', value: `/${relative(s)}?v=${timestamp()}`},
	]);
	treeAdapter.appendChild(body, moduleScript);
	} else {
	// Other filenames we assume are for non-ESModule browsers, so if the file has a matching
	// ESModule script we add a 'nomodule' attribute
	function hasMatchingModule(file, files) {
	const noExt = file.substring(0, file.length - 3);
	const testMjs = (noExt + '.mjs').toLowerCase();
	const testEs2015 = (noExt + '.es2015.js').toLowerCase();
	const matches = files.filter(t => {
	const lc = t.toLowerCase();
	return lc === testMjs \|\| lc === testEs2015;
	});
	return matches.length > 0;
	}

	// Note: empty string value is equivalent to a bare attribute, according to
	// https://github.com/inikulin/parse5/issues/1
	const nomodule = hasMatchingModule(s, jsFiles) ? [{name: 'nomodule', value: ''}] : [];

	const noModuleScript = treeAdapter.createElement('script', undefined, nomodule.concat([
	{name: 'src', value: `/${relative(s)}?v=${timestamp()}`},
	]));
	treeAdapter.appendChild(body, noModuleScript);
	}
	}

	for (const s of params.filter(s => /\.css$/.test(s))) {
	const stylesheet = treeAdapter.createElement('link', undefined, [
	{name: 'rel', value: 'stylesheet'},
	{name: 'href', value: `/${relative(s)}?v=${timestamp()}`},
	]);
	treeAdapter.appendChild(head, stylesheet);
	}

	const content = parse5.serialize(document, {treeAdapter});
	write(outputFile, content, {encoding: 'utf-8'});
	return 0;
	}

	module.exports = {main};

	if (require.main === module) {
	// We always require the arguments are encoded into a flagfile
	// so that we don't exhaust the command-line limit.
	const params = fs.readFileSync(process.argv[2], {encoding: 'utf-8'}).split('\n').filter(l => !!l);
	process.exitCode = main(params);
	}