The NextJS bundle analyzer gives some output like this:
Page Size First Load JS
┌ λ / 12 kB 368 kB
├ └ 79.202101.46dabc.chunk.css 10.3 kB
...
+ First Load JS shared by all 195 kB
├ chunks/0e69992b3e9a8d51f37748cf97b75268d47a0f0c.f372af.js 27.6 kB
├ chunks/cf0e5769c2fa5761a95adfa95a4e062fb86f8f05.272397.js 91.4 kB
├ chunks/commons.9707f2.js 9.01 kB
├ chunks/framework.efaa9a.js 46.9 kB
├ chunks/main.9965a5.js 6.39 kB
├ chunks/pages/_app.a4ce0d.js 11.4 kB
├ chunks/webpack.8e3a04.js 2.72 kB
└ 62.202101.796f1f.chunk.css 3.7 kB
What exactly does “First Load JS” measure and why does it not equal the sum of “First Load JS shared by all” and the size of the page and it’s sub-pages. I.e. based on this output I would expect First Load JS to equal 12 kb + 10.3 kb + 195 kb, not 368 kb.
Thanks.