//
JsFor toFor = new JsFor();
// The first item is either an expression or a JsVars.
//
JsNode initThingy = map(fromInit);
if (initThingy != null) {
if (initThingy instanceof JsVars) {
toFor.setInitVars((JsVars) initThingy);
} else {
assert (initThingy instanceof JsExpression);