The source code typically contains inline scripts that function as a "bootloader." Rather than loading all JavaScript dependencies synchronously—which would block the rendering of the page—Facebook utilizes dynamic script insertion. These scripts often reference a Bootloader object, which manages the asynchronous fetching of "chunks" of code required for specific features.
This indicates an aggressive cache-busting and long-term caching strategy:
React, the library developed by and used extensively by Facebook, relies on a process called hydration. The source code reveals pre-rendered HTML structures inside hidden elements or specific containers. Simultaneously, the large JSON payloads found within <script> tags represent the state of the application. When the JavaScript bundle loads, it does not re-fetch this data; instead, it "hydrates" the existing HTML, attaching event listeners and reconciling the state.
The source code typically contains inline scripts that function as a "bootloader." Rather than loading all JavaScript dependencies synchronously—which would block the rendering of the page—Facebook utilizes dynamic script insertion. These scripts often reference a Bootloader object, which manages the asynchronous fetching of "chunks" of code required for specific features.
This indicates an aggressive cache-busting and long-term caching strategy:
React, the library developed by and used extensively by Facebook, relies on a process called hydration. The source code reveals pre-rendered HTML structures inside hidden elements or specific containers. Simultaneously, the large JSON payloads found within <script> tags represent the state of the application. When the JavaScript bundle loads, it does not re-fetch this data; instead, it "hydrates" the existing HTML, attaching event listeners and reconciling the state.