js--function-prologue-beginning

js--function-prologue-beginning is a compiled Lisp function in `js.el'.

(js--function-prologue-beginning &optional POS)

Return the start of the JavaScript function prologue containing POS.
A function prologue is everything from start of the definition up
to and including the opening brace. POS defaults to point.
If POS is not in a function prologue, return nil.