Deferred Loading

Post-Render Loading, hydration

Unblock rendering for optimal user experience. But beware the uncanny valley of non-interactive pages! Gap events

• async attribute
  • Load order not guaranteed, so one script can’t depend on another
  • Good for stand-alone scripts like analytics
• defer attribute
  • Still executed in order
  • Low browser support?
• https://stackoverflow.com/questions/10808109/script-tag-async-defer#10808243

Lazy Loading

Loading features/sections of your JS app as requested.

• Dynamic import()
  • Proposed to TC39
  • Available via Webpack
• SystemJS
• Not broadly supported
  • <script type=”module”> - (not Firefox)
  • https://hacks.mozilla.org/2015/08/es6-in-depth-modules/