Add red box prototype

packages/react-dev-utils/failFast.js

@@ -0,0 +1,77 @@
+(function() {
+  const ErrorStackParser = require('error-stack-parser')
+
+  const overlayStyle = {
+    position: 'fixed',
+    'box-sizing': 'border-box',
+    top: '0px', left: '0px',
+    bottom: '0px', right: '0px',
+    width: '100vw', height: '100vh',
+    'background-color': 'rgb(200, 0, 0)',
+    padding: '2rem',
+    'z-index': 1337,
+    'font-family': 'Menlo, Consolas, monospace',
+    color: 'rgb(232, 232, 232)',
+    'white-space': 'pre-wrap'
+  }
+
+  const headerStyle = {
+    'font-size': 'larger',
+    'font-weight': 'bold'
+  }
+
+  const traceStyle = {
+    'font-size': '1rem'
+  }
+
+  function applyStyles(element, styles) {
+    element.setAttribute('style', '')
+    for (const key in styles) {
+      if (!styles.hasOwnProperty(key)) continue
+      element.style[key] = styles[key].toString()
+    }
+  }
+
+  function render(name, message, frames) {
+    // Create container
+    const overlay = document.createElement('div')
+    applyStyles(overlay, overlayStyle)
+
+    // Create header
+    const header = document.createElement('div')
+    applyStyles(header, headerStyle)
+    header.appendChild(document.createTextNode(`${name}: ${message}`))
+    overlay.appendChild(header)
+
+    // Show trace
+    const trace = document.createElement('div')
+    applyStyles(trace, traceStyle)
+    for (const frame of frames) {
+      const { source } = frame
+      const elem = document.createElement('div')
+      elem.appendChild(document.createTextNode(source))
+      trace.appendChild(elem)
+    }
+    overlay.appendChild(trace)
+
+    // Mount
+    document.body.appendChild(overlay)
+  }
+
+  function crash(error) {
+    let frames = []
+    try {
+      frames = ErrorStackParser.parse(error)
+    } catch (e) {
+    }
+    render(error.name, error.message, frames)
+  }
+
+  window.onerror = function(messageOrEvent, source, lineno, colno, error) {
+    if (error == null || !(error instanceof Error) || messageOrEvent.indexOf('Script error') !== -1) {
+      crash(new Error('Unknown script error.'))// TODO: more helpful message
+    } else {
+      crash(error)
+    }
+  }
+})()

packages/react-dev-utils/package.json

@@ -11,8 +11,9 @@
     "node": ">=4"
   },
   "files": [
-    "clearConsole.js",
     "checkRequiredFiles.js",
+    "clearConsole.js",
+    "failFast.js",
     "formatWebpackMessages.js",
     "getProcessForPort.js",
     "InterpolateHtmlPlugin.js",
@@ -25,6 +26,7 @@
   "dependencies": {
     "ansi-html": "0.0.5",
     "chalk": "1.1.3",
+    "error-stack-parser": "1.3.6",
     "escape-string-regexp": "1.0.5",
     "html-entities": "1.2.0",
     "opn": "4.0.2",

packages/react-scripts/config/webpack.config.dev.js

@@ -53,6 +53,8 @@ module.exports = {
     require.resolve('react-dev-utils/webpackHotDevClient'),
     // We ship a few polyfills by default:
     require.resolve('./polyfills'),
+    // In development, we want to fail fast
+    require.resolve('react-dev-utils/failFast'),
     // Finally, this is your app's code:
     paths.appIndexJs
     // We include the app code last so that if there is a runtime error during