flamescope VS create-react-app

Netflix's flamescope

I searched over the web how to profile C extensions for Ruby and C code in general, and found out Brendan Gregg’s tutorial on Linux perf. That was my first usage of Linux perf profiler. I’ve also tried gperftools and pprof, because seen its usage. And flamescope, because it was made by Brendan Gregg. There are many similar tools and it was hard to figure out what to use during two weeks or so.

We recommend going through the tutorial on building a tic-tac-toe game on the React homepage to get a feel of what React is and what it does. For more in-depth learning, check out the Egghead course, Build Your First Production Quality React App. It covers some advanced concepts and real-world usages that are not covered by the React documentation. Create React App by Facebook is a tool to scaffold a React project with minimal configuration and is highly recommended to use for starting new React projects.

Creating React App is a comfortable environment for learning React, and is the best way to start building a new single-page application in React.

I'm using facebook's create-react app for my application:

I'm developing a React app created with "create react app" (https://github.com/facebookincubator/create-react-app). It will be hosted in Firebase Hosting and I'll like to use implicit initialization as describe in documentation (https://firebase.google.com/docs/web/setup#sdk_imports_and_implicit_initialization), to deploy to multiple projects (I have a dev project and several production projects)

I am working on a website that I used create-react-app to create. I need to make a contact page where the information entered will be sent to a specified email.

'use strict';const autoprefixer = require('autoprefixer');const path = require('path');const webpack = require('webpack');const HtmlWebpackPlugin = require('html-webpack-plugin');const CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');const WatchMissingNodeModulesPlugin = require('react-dev-utils/WatchMissingNodeModulesPlugin');const eslintFormatter = require('react-dev-utils/eslintFormatter');const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');const getClientEnvironment = require('./env');const paths = require('./paths');const ExtractTextPlugin = require('extract-text-webpack-plugin');// Webpack uses `publicPath` to determine where the app is being served from.// In development, we always serve from the root. This makes config easier.const publicPath = '/';// `publicUrl` is just like `publicPath`, but we will provide it to our app// as %PUBLIC_URL% in `index.html` and `process.env.PUBLIC_URL` in JavaScript.// Omit trailing slash as %PUBLIC_PATH%/xyz looks better than %PUBLIC_PATH%xyz.const publicUrl = '';// Get environment variables to inject into our app.const env = getClientEnvironment(publicUrl);// This is the development configuration.// It is focused on developer experience and fast rebuilds.// The production configuration is different and lives in a separate file.module.exports = { // You may want 'eval' instead if you prefer to see the compiled output in DevTools. // See the discussion in https://github.com/facebookincubator/create-react-app/issues/343. devtool: 'cheap-module-source-map', // These are the "entry points" to our application. // This means they will be the "root" imports that are included in JS bundle. // The first two entry points enable "hot" CSS and auto-refreshes for JS. entry: [ // Include an alternative client for WebpackDevServer. A client's job is to // connect to WebpackDevServer by a socket and get notified about changes. // When you save a file, the client will either apply hot updates (in case // of CSS changes), or refresh the page (in case of JS changes). When you // make a syntax error, this client will display a syntax error overlay. // Note: instead of the default WebpackDevServer client, we use a custom one // to bring better experience for Create React App users. You can replace // the line below with these two lines if you prefer the stock client: // require.resolve('webpack-dev-server/client') + '?/', // require.resolve('webpack/hot/dev-server'), require.resolve('react-dev-utils/webpackHotDevClient'), // We ship a few polyfills by default: require.resolve('./polyfills'), // Errors should be considered fatal in development require.resolve('react-error-overlay'), // Finally, this is your app's code: paths.appIndexJs, // We include the app code last so that if there is a runtime error during // initialization, it doesn't blow up the WebpackDevServer client, and // changing JS code would still trigger a refresh. ], output: { // Next line is not used in dev but WebpackDevServer crashes without it: path: paths.appBuild, // Add /* filename */ comments to generated require()s in the output. pathinfo: true, // This does not produce a real file. It's just the virtual path that is // served by WebpackDevServer in development. This is the JS bundle // containing code from all our entry points, and the Webpack runtime. filename: 'static/js/bundle.js', // There are also additional JS chunk files if you use code splitting. chunkFilename: 'static/js/[name].chunk.js', // This is the URL that app is served from. We use "/" in development. publicPath: publicPath, // Point sourcemap entries to original disk location (format as URL on Windows) devtoolModuleFilenameTemplate: info => path.resolve(info.absoluteResourcePath).replace(/\\/g, '/'), }, resolve: { // This allows you to set a fallback for where Webpack should look for modules. // We placed these paths second because we want `node_modules` to "win" // if there are any conflicts. This matches Node resolution mechanism. // https://github.com/facebookincubator/create-react-app/issues/253 modules: ['node_modules', paths.appNodeModules].concat( // It is guaranteed to exist because we tweak it in `env.js` process.env.NODE_PATH.split(path.delimiter).filter(Boolean) ), // These are the reasonable defaults supported by the Node ecosystem. // We also include JSX as a common component filename extension to support // some tools, although we do not recommend using it, see: // https://github.com/facebookincubator/create-react-app/issues/290 // `web` extension prefixes have been added for better support // for React Native Web. extensions: ['.web.js', '.js', '.json', '.web.jsx', '.jsx'], alias: { // Support React Native Web // https://www.smashingmagazine.com/2016/08/a-glimpse-into-the-future-with-react-native-for-web/ 'react-native': 'react-native-web', }, plugins: [ // Prevents users from importing files from outside of src/ (or node_modules/). // This often causes confusion because we only process files within src/ with babel. // To fix this, we prevent you from importing files out of src/ -- if you'd like to, // please link the files into your node_modules/ and let module-resolution kick in. // Make sure your source files are compiled, as they will not be processed in any way. new ModuleScopePlugin(paths.appSrc), ], }, module: { strictExportPresence: true, rules: [ // TODO: Disable require.ensure as it's not a standard language feature. // We are waiting for https://github.com/facebookincubator/create-react-app/issues/2176. // { parser: { requireEnsure: false } }, // First, run the linter. // It's important to do this before Babel processes the JS. { test: /\.(js|jsx)$/, enforce: 'pre', use: [ { options: { formatter: eslintFormatter, }, loader: require.resolve('eslint-loader'), }, ], include: paths.appSrc, }, // ** ADDING/UPDATING LOADERS ** // The "file" loader handles all assets unless explicitly excluded. // The `exclude` list *must* be updated with every change to loader extensions. // When adding a new loader, you must add its `test` // as a new entry in the `exclude` list for "file" loader. // "file" loader makes sure those assets get served by WebpackDevServer. // When you `import` an asset, you get its (virtual) filename. // In production, they would get copied to the `build` folder. { exclude: [ /\.html$/, /\.(js|jsx)$/, /\.css$/, /\.json$/, /\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/, /\.scss$/ ], loader: require.resolve('file-loader'), options: { name: 'static/media/[name].[hash:8].[ext]', }, }, // "url" loader works like "file" loader except that it embeds assets // smaller than specified limit in bytes as data URLs to avoid requests. // A missing `test` is equivalent to a match. { test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/], loader: require.resolve('url-loader'), options: { limit: 10000, name: 'static/media/[name].[hash:8].[ext]', }, }, // Process JS with Babel. { test: /\.(js|jsx)$/, include: paths.appSrc, loader: require.resolve('babel-loader'), options: { // This is a feature of `babel-loader` for webpack (not Babel itself). // It enables caching results in ./node_modules/.cache/babel-loader/ // directory for faster rebuilds. cacheDirectory: true, }, }, // "postcss" loader applies autoprefixer to our CSS. // "css" loader resolves paths in CSS and adds assets as dependencies. // "style" loader turns CSS into JS modules that inject tags. // In production, we use a plugin to extract that CSS to a file, but // in development "style" loader enables hot editing of CSS. { test: /\.css$/, use: [ require.resolve('style-loader'), { loader: require.resolve('css-loader'), options: { importLoaders: 1, modules: true, localIdentName: "[name]__[local]___[hash:base64:5]" }, }, { loader: require.resolve('postcss-loader'), options: { // Necessary for external CSS imports to work // https://github.com/facebookincubator/create-react-app/issues/2677 ident: 'postcss', plugins: () => [ require('postcss-flexbugs-fixes'), autoprefixer({ browsers: [ '>1%', 'last 4 versions', 'Firefox ESR', 'not ie < 9', // React doesn't support IE8 anyway ], flexbox: 'no-2009', }), ], }, }, ], }, { test: /\.scss$/, use: ExtractTextPlugin.extract({ fallback:'style-loader', use: [ { loader: 'css-loader', q: { modules: true, sourcemap: true, importLoaders: 2, localIdentName: '[name]__[local]__[hash:base64:5]' } }, 'sass-loader' ] }), loaders: [ require.resolve('style-loader'), require.resolve('css-loader'), require.resolve('sass-loader') ] } // ** STOP ** Are you adding a new loader? // Remember to add the new extension(s) to the "file" loader exclusion list. ], }, plugins: [ // Makes some environment variables available in index.html. // The public URL is available as %PUBLIC_URL% in index.html, e.g.: // // In development, this will be an empty string. new InterpolateHtmlPlugin(env.raw), // Generates an `index.html` file with the injected. new HtmlWebpackPlugin({ inject: true, template: paths.appHtml, }), // Add module names to factory functions so they appear in browser profiler. new webpack.NamedModulesPlugin(), // Makes some environment variables available to the JS code, for example: // if (process.env.NODE_ENV === 'development') { ... }. See `./env.js`. new webpack.DefinePlugin(env.stringified), // This is necessary to emit hot updates (currently CSS only): new webpack.HotModuleReplacementPlugin(), // Watcher doesn't work well if you mistype casing in a path so we use // a plugin that prints an error when you attempt to do this. // See https://github.com/facebookincubator/create-react-app/issues/240 new CaseSensitivePathsPlugin(), // If you require a missing module and then `npm install` it, you still have // to restart the development server for Webpack to discover it. This plugin // makes the discovery automatic so you don't have to restart. // See https://github.com/facebookincubator/create-react-app/issues/186 new WatchMissingNodeModulesPlugin(paths.appNodeModules), // Moment.js is an extremely popular library that bundles large locale files // by default due to how Webpack interprets its code. This is a practical // solution that requires the user to opt into importing specific locales. // https://github.com/jmblog/how-to-optimize-momentjs-with-webpack // You can remove this if you don't use Moment.js: new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/), new ExtractTextPlugin({'styles.css'}), ], // Some libraries import Node modules but don't use them in the browser. // Tell Webpack to provide empty mocks for them so importing them works. node: { dgram: 'empty', fs: 'empty', net: 'empty', tls: 'empty', }, // Turn off performance hints during development because we don't do any // splitting or minification in interest of speed. These warnings become // cumbersome. performance: { hints: false, },}; </code> Modal.js file :</p> <p><code> import React from "react";import ReactDOM from "react-dom";// import styles from "../css/popUpBox.css";import styles from "../css/modal.scss"; // ERROR HAPPENS HERE!! </code> ...file continues </p> <p>Package.json :</p> <p><code> { "name": "react-hackboard", "version": "0.1.0", "private": true, "dependencies": { "autoprefixer": "7.1.1", "babel-core": "6.25.0", "babel-eslint": "7.2.3", "babel-jest": "20.0.3", "babel-loader": "7.0.0", "babel-preset-react-app": "^3.0.1", "babel-runtime": "6.23.0", "case-sensitive-paths-webpack-plugin": "2.1.1", "chalk": "1.1.3", "css-loader": "0.28.4", "dotenv": "4.0.0", "eslint": "3.19.0", "eslint-config-react-app": "^1.0.5", "eslint-loader": "1.7.1", "eslint-plugin-flowtype": "2.34.0", "eslint-plugin-import": "2.2.0", "eslint-plugin-jsx-a11y": "5.0.3", "eslint-plugin-react": "7.1.0", "extract-text-webpack-plugin": "2.1.2", "file-loader": "0.11.2", "fs-extra": "3.0.1", "html-webpack-plugin": "2.29.0", "jest": "20.0.4", "node-sass": "^4.5.3", "object-assign": "4.1.1", "postcss-flexbugs-fixes": "3.0.0", "postcss-loader": "2.0.6", "promise": "7.1.1", "react": "^15.6.1", "react-dev-utils": "^3.0.2", "react-dom": "^15.6.1", "react-error-overlay": "^1.0.9", "react-redux": "^5.0.5", "redux": "^3.7.2", "redux-createreducer": "^2.0.0", "redux-thunk": "^2.2.0", "sass-loader": "^6.0.6", "style-loader": "0.18.2", "sw-precache-webpack-plugin": "0.11.3", "url-loader": "0.5.9", "webpack": "2.6.1", "webpack-dev-server": "2.5.0", "webpack-manifest-plugin": "1.1.0", "whatwg-fetch": "2.0.3" }, "scripts": { "start": "node scripts/start.js", "build": "node scripts/build.js", "test": "node scripts/test.js --env=jsdom" }, "jest": { "collectCoverageFrom": [ "src/**/*.{js,jsx}" ], "setupFiles": [ "<rootDir>/config/polyfills.js" ], "testMatch": [ "<rootDir>/src/**/__tests__/**/*.js?(x)", "<rootDir>/src/**/?(*.)(spec|test).js?(x)" ], "testEnvironment": "node", "testURL": "http://localhost", "transform": { "^.+\\.(js|jsx)$": "<rootDir>/node_modules/babel-jest", "^.+\\.css$": "<rootDir>/config/jest/cssTransform.js", "^(?!.*\\.(js|jsx|css|json)$)": "<rootDir>/config/jest/fileTransform.js" }, "transformIgnorePatterns": [ "[/\\\\]node_modules[/\\\\].+\\.(js|jsx)$" ], "moduleNameMapper": { "^react-native$": "react-native-web" }, "moduleFileExtensions": [ "web.js", "js", "json", "web.jsx", "jsx" ] }, "babel": { "presets": [ "react-app" ] }, "eslintConfig": { "extends": "react-app" }, "devDependencies": { "node-sass": "^4.5.3", "sass-loader": "^6.0.6", "webpack": "^2.6.1" }} </code></p> <p>Answer link : <a href="https://codehunter.cc/a/reactjs/module-not-found-cant-resolve-style">https://codehunter.cc/a/reactjs/module-not-found-cant-resolve-style</a></p> </div><!-- SC_ON -->

Is there a way to specify caching headers somewhere in my react project? I also read over the create-react-app user guide, and they say you can use a .htaccess file for Apache HTTP server. Is there something similar to that I should be leveraging?

I started an app using create-react-app, and I have this Error Boundary component:

UPDATE: The app was created using create-react-app 1.0.17 and later ejected.

I've created a React application with create-react-app