WebExtension Plugin

This is shared source code for the Chrome and Firefox extensions.

Changes to this code should be tested in both browsers before being submitted. Refer to the instructions in shells/chrome and shells/firefox for how to test each browser.

Insulating the environment

React DevTools has part of the code (the backend + agent) running in the same javascript context as the inspected page, which makes the code vulnerable to environmental inconsistencies. For example, the backend uses the es6 Map class and normally expects it to be available in the global scope. If a user script has overridden this, the backend breaks.

To prevent this, the content script src/GlobalHook.js, which runs before any user js, saves the native values we depend on to the __REACT_DEVTOOLS_GLOBAL_HOOK__ global. These are:

• Set
• Map
• WeakMap
• Object.create

Then in webpack.backend.js, these saved values are substituted for the globally referenced name (e.g. Map gets replaced with window.__REACT_DEVTOOLS_GLOBAL_HOOK__.nativeMap).

Fixing document.create

React Native sets document.createElement to null in order to convince js libs that they are not running in a browser environment while debug in chrome is enabled.

To deal with this, src/inject.js calls document.constructor.prototype.createElement when it needs to create a <script> tag.