Fix "SyntaxError: Unexpected identifier 'each'" in Apps Script V8

SyntaxError: Unexpected identifier 'each'

You get this the moment a project switches from the Rhino runtime to V8 (or when Google force-migrates it). The whole file fails to load, so every function in it stops — triggers, menus, web apps.

Why it happens

for each (var x in obj) was a JavaScript 1.6 extension. Rhino accepted it and looped over values. It never became standard ECMAScript, and V8 rejects it at parse time.

The fix

Loop over values with for…of:

// Rhino
for each (var row in rows) {
  total += row[2];
}

// V8 — arrays
for (var row of rows) {
  total += row[2];
}

// V8 — plain objects (values)
for (var value of Object.values(obj)) {
  Logger.log(value);
}

Google's migration guide suggests the equivalent for (var key in obj) { var value = obj[key]; … }.

Rhino	V8
`for each (var v in array)`	`for (const v of array)`
`for each (var v in object)`	`for (const v of Object.values(object))`
`[x * 2 for each (x in a)]` (array comprehension)	`a.map((x) => x * 2)`
`for each (var item in xml..item)` (E4X)	`root.getDescendants()` via XmlService — see the E4X guide

Gotchas

for…in (without each) gives keys, not values. Swapping only the keyword silently changes behaviour.
for each over null did nothing in Rhino; for…of null throws. V8Shift writes Object.values(x || {}) to keep the Rhino behaviour.
Array comprehensions and generator expressions using for each need a .map() / .filter() rewrite.

How V8Shift handles it

Every for each statement is rewritten automatically to for (… of Object.values(…)). Comprehensions are listed in the manual checklist with file and line.