A node application has required me to run node with a harmony flag, like:
node --harmony app.js
What is this harmony flag? What does it do and why can't the app run without it?
I've tried looking into node command-line options (node --help), but it doesn't provide any details either. Node docs weren't of any help either.
Typing man node has this on the harmony flag:
--harmony_typeof (enable harmony semantics for typeof)
type: bool default: false
--harmony_scoping (enable harmony block scoping)
type: bool default: false
--harmony_modules (enable harmony modules (implies block scoping))
type: bool default: false
--harmony_proxies (enable harmony proxies)
type: bool default: false
--harmony_collections (enable harmony collections (sets, maps, andweak maps))
type: bool default: false
--harmony (enable all harmony features (except typeof))
type: bool default: false
So --harmony is a shortcut to enable all the harmony features (e.g. --harmony_scoping, --harmony_proxies, etc.) From this blog post, it seems harmony enables new ECMAScript 6 features in the language. The reason your file won't run without harmony is because app.js is probably using non-backward compatible features from the new ECMAScript 6 standard (like block scoping, proxies, sets, maps, etc.)
