demo · v132

Lazy vs eager parsing, side-by-side

When you call a function the engine has to do three things: parse, compile, execute. Without hints, V8 lazy-parses every function and re-parses on first call. The magic comment //#allFunctionsCalledOnLoad opts the file into eager compilation. Simulate which functions get called and watch the trade-off.

lazy (default)

no hint — every called fn is re-parsed at first call

script eval—
tti contribution—

eager (magic comment)

//#allFunctionsCalledOnLoad — everything parsed up-front

script eval—
tti contribution—
parse compile execute

your bundler annotation

// at top of bundle.js
//#allFunctionsCalledOnLoad

function init() { ... }
function renderLayout() { ... }
function attachEventHandlers() { ... }
// V8 eagerly parses and compiles all three immediately

see also