When you crate a new Google Apps Script, it seems to support the v8 runtime by default. The documentation states:
Apps Script supports two JavaScript runtimes: the modern V8 runtime and an older one powered by Mozilla’s Rhino JavaScript interpreter.
The V8 runtime supports modern ECMAScript syntax and features.
The V8 runtime documentation states:
You can use modern ECMAScript syntax in scripts that are powered by the V8 runtime. This syntax includes let, const, and many other popular features.
In both cases, they are very vague as to which ECMAScript version is supported, simply stating “modern ECMAScript syntax”. This is problematic because there are 7 versions that were released between 2015 and 2021. Thus “modern” could refer to any one of these versions.
For example, I could easily assume that “modern” refers to the latest, 12th edition (2022) of ECMAScript, and end up writing code like this:
let a = 1_000;
However, attempting to use that syntax leads to the error:
Syntax error: ParseError: Unexpected token ILLEGAL line: …
Rather than manually go through each of the remaining 6 versions until I find the latest one supported, it would be great to find documentation that explicitly states which ECMAScript version is supported.
Note: The previous related question (Which Edition of ECMA-262 Does Google Apps Script Support?) is not helpful since those answers also refer to “modern ECMAScript” rather than a definitive, specific version.
Which version of ECMAScript is supported by the V8 runtime?