Statements

Inside function bodies and closure blocks { … }, you can use the following statements.

Forms

Statement	Syntax sketch
Return	return expr [ ';' ]
Fail	fail skip ( expr ) or fail stop ( expr ) (strategy + cause)
Const	const name = expr ';'
Let	let name = expr ';'
Assign	name = expr ';'
If / else	if '(' cond ')' block ( else if ... )* [ else block ]
While	while '(' cond ')' block
For	for '(' binding in iterable ')' block
Do-while	do block while '(' cond ')'
Break	break [ expr ] [ ';' ]
Continue	continue [ ';' ]
Expression	expr ';'

A semicolon may be omitted in some positions (e.g. return before }).

Blocks

A block is { zero or more statements }.

Module scope vs function body

At namespace scope, name = expr without const or let declares a module-level constant (this is how flow = … is written). Inside functions and closures, use const, let, or assignment statements as above.